Back Clinic Nerve Injury Team. Nerves are fragile and can be damaged by pressure, stretching, or cutting. Injury to a nerve can stop signals to and from the brain, causing muscles not to work properly and losing feeling in the injured area. The nervous system manages a great majority of the body’s functions, from regulating an individual’s breathing to controlling their muscles as well as sensing heat and cold. But, when trauma from an injury or an underlying condition causes nerve injury, an individual’s quality of life may be greatly affected. Dr. Alex Jimenez explains various concepts through his collection of archives revolving around the types of injuries and condition which can cause nerve complications as well as discuss the different form of treatments and solutions to ease nerve pain and restore the individual’s quality of life.
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When compared to other central nervous system (CNS) health issues, chronic neurodegenerative diseases can be far more complicated. Foremostly, because the compromised mitochondrial function has been demonstrated in many neurodegenerative diseases, the resulting problems in energy sources are not as severe as the energy collapse in ischemic stroke. Therefore, if excitotoxicity contributes to neurodegeneration, a different time of chronic excitotoxicity needs to be assumed. In the following article, we will outline what is known about the pathways that may cause excitotoxicity in neurodegenerative diseases. We will specifically discuss that in amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD) and Huntington’s disease (HD) as fundamental examples with sufficiently validated animal models in research studies. �
Amyotrophic Lateral Sclerosis
Amyotrophic lateral sclerosis (ALS) is a neurodegenerative disease associated with the degeneration of motor neurons which ultimately determine the length of the health issue. ALS is considered fatal several years after it begins. It is hypothesized that L-glutamate excitotoxicity plays a role in the motor neuron death in ALS because cells demonstrate increased levels of calcium-permeable AMPA receptors and low levels of calcium-binding proteins. Compared to the utilization of AMPA and kainate, and L-HCA, in the spinal cord of rats, treatment with NMDA spared motor neurons suggests that NMDA excitotoxicity may actually not play a fundamental role in ALS. However, NMDA receptor-mediated excitotoxicity in motor neurons was demonstrated in chick embryo organotypic slice cultures. Electrophysiological research studies suggested that transient hyperexcitability of motor nerves in the presymptomatic phase of ALS in mice transgenic for the G93A mutation of human SOD1 is associated with hereditary ALS. Additionally, cortical hyperexcitability was recorded in familial and sporadic ALS patients with the onset of symptoms in familial ALS mutation carriers. Moreover, the only approved drug and/or medication utilized for ALS, which increases survival by 2 to 3 months, acts as an inhibitor of both NMDA and kainate receptors together with quickly upregulating EAAT activity in synaptosomes, according to several research studies. �
In autopsied spinal cords from patients with ALS, several groups demonstrated a decrease in EAAT2 and not in EAAT1 protein expression in the gray matter of regions with considerable motor neuron loss. In addition, both L-glutamate uptake and EAAT2 immunoreactivity, as demonstrated by Western blotting, were demonstrated to be quantitatively decreased in postmortem tissue of ALS patients, particularly in the spinal cord, the tissue which is most commonly affected by the health issue. Additionally, it has been demonstrated that as a possible effect of EAAT2 downregulation, L-glutamate amounts are increased in the CSF in patients with ALS. However, this outcome measure couldn’t be replicated by other research studies. �
The downregulation of EAAT2 in human ALS is demonstrated in several animal models of ALS, including transgenic mice expressing human SOD1 containing the G93A mutation which causes hereditary ALS or transgenic rats expressing the same mutation. Surprisingly, “whereas Bendotti demonstrated a late decrease in EAAT2 expression at the time when the mice had already become symptomatic,” research studies demonstrated fluctuations in EAAT2 expression at the presymptomatic stage. The ?-lactam antibiotic ceftriaxone (Cef) promotes the production of EAAT2 in cultured murine spinal cord slices and in neuron/astrocyte co-cultures. In addition, it caused EAAT2 expression from the spinal cords of wild-type and mutant G93A mSOD1 Tg mice, which has been associated with a decrease in motor neuron loss, weight reduction, and other ALS-like symptoms as well as an increase in survival, compatible with the hypothesis that EAAT2 loss contributes to chronic excitotoxicity in this mouse model. Just recently, a significant decrease in EAAT2 immunoreactivity had been demonstrated in a separate bark model for ALS, rats expressing ALS-inducing mutant TAR DNA binding protein 43 in astrocytes only. Surprisingly, the research studies demonstrated that when measured by microdialysis, the extracellular L-glutamate and L-aspartate concentrations increase while the L-glutamate clearance capability decrease in the cerebral cortex of G93A mSOD1 Tg mice, however, this region doesn’t show overt pathology nor downregulation of EAAT1 when evaluated. �
Taken together these research studies support the view that there is a downregulation of EAAT2 in both human ALS patients and animal models of ALS. However, while some animal research studies suggest that EAAT2 downregulation occurs before motor neuron loss, others are compatible with the hypothesis that the downregulation of EAAT2, the astroglial expression of which is associated with the existence of neurons, is a consequence of neurodegeneration in neurological diseases. �
Furthermore, EAATs decrease extracellular L-glutamate, extracellular cerebral L-glutamate is upregulated in a variety of brain regions from the cystine/glutamate antiporter system x?c. XCT, one particular subunit of program x?c, was demonstrated to be differentially regulated and maintained in mouse models of ALS. Research studies demonstrated that the uptake of radiolabelled cystine was upregulated in spinal cord slices of presymptomatic G93A mSOD1 Tg mice at the age of 70 days but not in 55 or 100 days and not in symptomatic 130 day-old mice which also determined that the upregulation of cystine uptake at day 70 was because of system x?c activity utilizing the system x?c inhibitor sulfasalazine (SSZ). It needs to be considered, however, that cystine can also be hauled by EAATs. Therefore, as evidence about the SSZ-sensitivity of cystine uptakes were not demonstrated for days 100 and 130, the differential cystine uptake demonstrated in this research study at the older ages could rather be a result of decreased EAAT action. By comparison, research studies with rtPCR demonstrated a strong growth in xCT mRNA levels in G37R mSOD1 Tg mice on the beginning of symptoms, which has been further increased as symptoms improved. Moreover, it was demonstrated that xCT was primarily demonstrated in spinal cord microglial cells. Microglia revealed xCT mRNA upregulation in the presymptomatic stage. Taken together, these outcome measures suggest the system x?c is upregulated in animal models of ALS. However, the evidence is lacking about whether this is true for human cases of ALS. Nevertheless, further research studies revealed that the mRNA levels of CD68, a marker of microglial activation, were associated with xCT mRNA expression in postmortem spinal cord tissue of individuals with ALS, demonstrating that neuroinflammation in humans is also ultimately associated with xCT upregulation. �
Beyond the dysregulation of L-glutamate and L-aspartate levels by EAAT downregulation or system x?c upregulation, pathways that indirectly regulate and maintain glutamatergic neurotransmission also have been suggested to participate in motor neuron degeneration in ALS. D-Serine levels have been shown to become considerably increased from the spinal cord of G93A mSOD1 Tg mice. Starting at disease onset and ongoing during the course of this symptomatic phase, D-serine increases NMDA excitotoxicity in motor neurons. The upregulation of D-serine at the spinal cord was duplicated by other research studies. Downregulation of this D-serine metabolizing enzyme DAO in the reticulospinal tract has been demonstrated as the main mechanism for D-serine upregulation in the spinal cord in ALS mice. In addition, genetic inactivation of DAO in mice has been associated with motor neuron degeneration and a deficiency in the D-serine generating enzyme serine racemase prolonged survival in G93A mSOD1 Tg mice although it hastened neurodegenerative disease onset. A heterozygous mutation of DAO has been demonstrated to be separate from the ALS phenotype in a large family with hereditary ALS. However, this continues to be the only family determined where a DAO mutation is associated with ALS. �
Concerning the other amino acid co-agonist of the NMDA receptor, glycine, an increase in the CSF levels in patients with ALS was demonstrated by one group, however, it couldn’t be replicated by other research studies. Several research studies also determined that KYNA levels are upregulated in the CSF of bulbar ALS patients as well as those in end-stage ALS. Independently, it was revealed that tryptophan and KYN levels are increased in the CSF from ALS patients as compared to controls. Additionally, IDO was proven to be expressed in neurons and spinal cord microglia from patients with ALS, indicating that microglial activation may increase the conversion of tryptophan in ALS into KYN, among others. �
Multilayered evidence suggests that increased glutamatergic neurotransmission is within ALS and may ultimately cause neurodegeneration in neurodegenerative diseases, as shown in Figure 3. Downregulation of EAAT2 in astrocytes and upregulation of program x?forecast in the context of microglial activation was repeatedly documented. NMDA receptors by D-serine may also play a role in dysregulation. Moreover, the kynurenine pathway seems to be triggered in ALS. �
�
In many research studies, evidence and outcome measures have demonstrated that chronic excitotoxicity may be associated with a variety of neurodegenerative diseases, including AD, HD, and ALS, ultimately causing neurodegeneration and a variery of symptoms associated with the health issues. The purpose of the following article is to outline what may cause excitotoxicity in neurodegenerative diseases. We will discuss these in amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD) and Huntington’s disease (HD). – Dr. Alex Jimenez D.C., C.C.S.T. Insight – Dr. Alex Jimenez D.C., C.C.S.T. Insight
In the article above, we outlined what is known about the pathways which may cause excitotoxicity in neurodegenerative diseases. We also discussed that in amyotrophic lateral sclerosis (ALS), Alzheimer’s disease (AD) and Huntington’s disease (HD) as fundamental examples with sufficiently validated animal models in research studies. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. We use functional health protocols to treat injuries or chronic disorders of the musculoskeletal system. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Lewerenz, Jan, and Pamela Maher. �Chronic Glutamate Toxicity in Neurodegenerative Diseases-What Is the Evidence?� Frontiers in Neuroscience, Frontiers Media S.A., 16 Dec. 2015, www.ncbi.nlm.nih.gov/pmc/articles/PMC4679930/.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
�
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited.
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download �
* All of the above XYMOGEN policies remain strictly in force.
Excitotoxicity is characterized as an acute insult which causes nerve cell death due to the excessive activation of iGluRs. Acute excitotoxicity plays a fundamental role in a variety of central nervous system (CNS) health issues, including cerebral ischemia, TBI, and status epilepticus. The mechanisms for acute excitotoxicity are different for every health issue. �
With brain ischemia, L-glutamate-associated and L-aspartate-associated excitotoxicity happen within minutes due to the growth in extracellular cerebral L-glutamate as well as L-aspartate. Because these are also energy-dependent, the abrupt loss of energy due to the shut down of blood flow can ultimately breakdown the neuronal and astroglial membrane. In neurons, membrane depolarization contributes to vesicular discharge. Additionally, energy degradation may even cause a change in their action, therefore, causing L-glutamate and L-aspartate to activate and affect ionic homeostasis which can interrupt EAAT action. The activation of L-glutamate/L-aspartate contributes to excitotoxicity through the over-activation of iGluRs of the NMDA type as demonstrated by the efficiency of NMDA antagonists in animal models of transient cerebral ischemia. �
In TBI, the mechanical tissue damage and the disruption of the blood-brain barrier can trigger acute secondary neurodegeneration, which, together with neuroinflammation and oxidative stress, is associated with L-glutamate activation from intracellular compartments and, therefore, by acute excitotoxicity. Moveover, acute application of the NMDA antagonist MK801 following TBI ameliorates neuronal loss and long-term behavioral abnormalities, among others. �
In status epilepticus, continuing the synchronized activity of excitatory neuronal networks as well as the continuous breakdown of restricting mechanisms is the main source of L-glutamate and L-aspartate activation. As the severity of synchronous activity depends upon the involvement of nerve cells into a neuronal system as well as the capability of a neural cell to withstand excess glutamate mainly depends on the expression pattern of iGluRs, a somewhat restricted and maturation-associated degeneration of neuronal populations which is ultimately caused by prolonged epileptic seizures. The significance of excitotoxicity in status epilepticus is shown as NMDA antagonists, such as ketamine, decrease adrenal loss. �
Excitotoxicity in Neurological Diseases
Because EAATs were discovered to be down-regulated in a variety of central nervous system (CNS) health issues and L-glutamate, as well as L-aspartate, clearance can ultimately affect the excitotoxicity of neurological diseases, many healthcare professionals have decided to determine substances which cause EAAT2, or the main EAAT in the brain and most commonly shown to be downregulated. This has demonstrated substances which shows astrocytic EAAT2 expression both in vitro and in vivo research studies. Several of these have also demonstrated protective properties in animal models of neurological diseases. Cef is one of the most evaluated compounds and it has been analyzed in AD, HD, and ALS models with positive outcomes. However, none of the substances has been extensively researched for its capability to interact with other neuroprotective pathways. Cef has also been demonstrated to promote EAAT2 expression but also to trigger the transcription factor Nrf2, which results in the transcription of a wide array of genes involved in cytoprotection and antioxidant protection. Because oxidative stress is believed to play an essential role in many, if not all, neurological diseases, this pathway may account for the neuroprotection caused by Cef. Furthermore, xCT, which can be one of the downstream targets of Nrf2, has been demonstrated to be upregulated by Cef in vitro and in vivo. Another in vitro EAAT2-promoting substance, MS-153, efficiently protected against secondary neurodegeneration after traumatic brain injury as well as through mechanisms other than EAAT2 upregulation. Evidence of concept experiments which demonstrate the increased stimulation through iGluRs in neurodegenerative diseases needs manipulations of their neurotransmitter physiology. �
Glud1 Tg mice demonstrate a model of excitotoxicity associated with enhanced synaptic L-glutamate activation with restricted neuronal loss. However, this animal model of glutamatergic neurotransmission has not yet been utilized to analyze if Glud1 over-expression aggravates the phenotype of mouse models in neurological diseases. Another version involves the EAAT2-deficient mouse. Homozygous EAAT2 knock-out mice have health issues associated with premature death because of epilepsy as well as hippocampal and focal cortical atrophy. Heterozygous EAAT2 knock-out mice, however, develop normally and show only mild behavioral abnormalities. This mouse model of moderate glutamate hyperfunction has been utilized in a collection of evidence of principle research studies which demonstrated the fundamental role of glutamate. ALS mice, which have both the G93A mSOD1 mutation and a decreased quantity of EAAT2 (SOD1(G93A)/EAAT2�), revealed an increase in the speed of motor decline accompanied by earlier motor neuron loss when compared with single mutant G93A mSOD1 Tg mice. A decrease in survival was also demonstrated in these mutant mice. When crossed with transgenic mice expressing mutations of the human amyloid-? protein precursor and presenilin-1 (A?PPswe/PS1?E9), partial loss of EAAT2 unmasked spatial memory deficits in 6-month-old mice expressing A?PPswe/PS1?E9. These mice demonstrated an increase in the ratio of detergent-insoluble A?42/A?40 demonstrating that shortages in glutamate transporter function ultimately cause premature pathogenic processes associated with AD. By comparison, the phenotype of the R6/2 HD mouse model wasn’t changed in mice which had only one EAAT2 allele. Further research studies are still necessary for further evidence. �
As a complement to these research studies, transgenic mice which over-express EAAT2 in astrocytes through the GFAP promoter has also been developed. EAAT2/G93A mSOD1 double Tg mice demonstrated moderate amelioration of their ALS-like phenotype with a statistically significant (14 times ) delay in grip power decrease and loss of motor neurons as well as a decrease in other occasions, such as caspase-3 activation and SOD1, although not at the beginning of paralysis, weight loss or an extended life span when compared with monotransgenic G93A mSOD1 littermates. Exactly the same EAAT2 transgenic mouse model was utilized to evaluate the effect of improved astrocytic L-glutamate and L-aspartate uptake by cross-breeding with an animal model of AD, A?PPswe/Ind mice. Increased EAAT2 protein levels considerably increased and improved overall cognitive functioning, restored synaptic ethics, and decreased amyloid plaques in those AD mice. �
In mice in which genetically engineered regulation and management of xCT causes a lack in the glutamate/cystine antiporter system x?c, the obvious decrease of extrasynaptic L-glutamate is associated with the tremendous resistance of dopaminergic neurons against 6-hydroxydopamine-induced neurodegeneration, perhaps as a consequence of reduced excitotoxicity. However, microglial activation has also been demonstrated to be modulated by system x?c deficiencies leading to a more neuroprotective phenotype which offers an explanation for the protective effect of xCT deletion in this circumstance. �
Therefore, genetic variations encourage the role of chronic excitotoxicity in neurodegenerative diseases, particularly AD and ALS. These models all represent life-long changes in glutamatergic neurotransmission. These models can’t determine if the utilization of drugs and/or medications can directly affect glutamate levels throughout the neurodegenerative process and/or be protective. Both evaluation and analysis of EAAT2-inducing medicine for the progression of inducible mouse models and their interaction with other signaling pathways is still warranted by researchers and healthcare professionals. �
In many research studies, evidence and outcome measures have demonstrated that glutamate dysregulation and excitotoxicity in many neurological diseases, including AD, HD, and ALS, ultimately lead to neurodegeneration and a variery of symptoms associated with the health issues. The purpose of the following article is to discuss and demonstrate the role that glutamate dysregulation and excitotoxicity plays on neurodegenerative diseases. The mechanisms for excitotoxicity are different for every health issue. – Dr. Alex Jimenez D.C., C.C.S.T. Insight – Dr. Alex Jimenez D.C., C.C.S.T. Insight
Metabolic Assessment Form
The following Metabolic Assessment Form can be filled out and presented to Dr. Alex Jimenez. Symptom groups listed on this form are not intended to be utilized as a diagnosis of any type of disease, condition, or any other type of health issue. �
Excitotoxicity is characterized as an acute insult which causes cell death due to the excess activation of iGluRs. Excitotoxicity plays a fundamental role in a variety of central nervous system (CNS) health issues, including cerebral ischemia, TBI, and status epilepticus. The mechanisms for acute excitotoxicity are different for every health issue. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. We use functional health protocols to treat injuries or chronic disorders of the musculoskeletal system. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Lewerenz, Jan, and Pamela Maher. �Chronic Glutamate Toxicity in Neurodegenerative Diseases-What Is the Evidence?� Frontiers in Neuroscience, Frontiers Media S.A., 16 Dec. 2015, www.ncbi.nlm.nih.gov/pmc/articles/PMC4679930/.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
�
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited.
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download �
* All of the above XYMOGEN policies remain strictly in force.
Previous research studies suggest that L-aspartate, like L-glutamate, triggers excitatory activity on neurons. L-aspartate functions with L-glutamate in the synaptic vesicles of asymmetric excitatory synapses. But, the total concentration of these in the human brain (0.96-1.62 ?mol/gram wet weight), their extracellular concentrations in the cortex as measured by microdialysis (1.62 ?M for L-aspartate and 9.06 ?M for L-glutamate) and their supply according to immunohistochemistry suggest that L-aspartate is significantly less abundant than L-glutamate. Moreover, L-aspartate is a powerful agonist for NMDA receptors but not for other iGluRs with an EC50 just eight-fold higher than that of L-glutamate. EAATs which play a fundamental role in the uptake of all vesicular released L-glutamate in the central nervous system (CNS) also requires the utilization of L-aspartate. L-aspartate is perhaps as less essential as L-glutamate connected to the total excitatory activity associated with iGluRs. Along with its role as a neurotransmitter, as previously mentioned, L-aspartate is also necessary as a substrate for aspartate amino-transferase which turns into 2-oxoglutarate and L-glutamate to transport to the cortical vesicles of glutamatergic neurons which may also consequently and indirectly increase L-glutamate release. �
Other Molecules in Glutamate Signaling
One characteristic which distinguishes NMDA receptors from different iGluRs is that the activation of NMDA receptors needs the connection of a co-agonist to the glycine binding region of the receptor. By way of instance, in the retina and in the spinal cord, the origin of glycine may spillover out of glycinergic inhibitory synapses. But, in different regions of the brain with increased NMDA receptor expression, such as the hippocampal formation, reactions associated with strychnine-sensitive glycine receptors are missing, at least in adult neurons, demonstrating the absence of glycinergic inhibitory neurotransmissions. But, glycine is found in the extracellular fluid of the hippocampus at baseline amounts of roughly 1.5 ?M, which is similar to the saturation of the glycine binding region of the NMDA receptor, although these may be up- and down-regulated. The origin of extracellular glycine in the hippocampus can be neurons which release glycine through the alanine-serine-cysteine amino acid transporter 1 (asc-1). But, glycine release by astrocytes that is stimulated by depolarization and kainate, has also been demonstrated. Further research studies are required to ultimately show these outcome measures. �
Even in previous research studies of the NMDA receptor and its co-activation by glycine revealed that D-amino acids, particularly D-serine, are nearly as powerful as glycine. Only several years after, it became obvious that D-serine is found in rat and human brains at roughly one-third of their concentration of L-serine having an absolute concentration of more than 0.2 ?mol/g brain tissue. Utilizing an antiserum for D-serine, research studies demonstrated that D-serine from the brain is only found in astrocytes and its supply fits the expression of NMDA receptors. In addition, the same researchers demonstrated that D-serine is released from cultured astrocytes when exposed to L-glutamate or kainate. The abundance of D-serine is found by the degrading enzyme D-amino acid oxidase (DAO) which reveals increased expression in the hindbrain where D-serine levels are reduced as well as the synthetic enzyme serine racemase which creates D-serine from L-serine. D-Serine appears to be stored in cytoplasmic vesicles in astrocytes and it can be released by exocytosis. Long-term potentiation is dependent upon D-serine release from astrocytes in hippocampal slices, suggesting that this amino acid definitely plays a fundamental role in glutamatergic neurotransmission through NMDA receptors. Additionally in hippocampal slices, research studies found, utilizing D-serine and glycine degrading enzymes, which D-serine functions as a co-transmitter for synaptic NMDA receptors on CA1 neurons likewise which glycine functions as the endogenous co-agonist for extrasynaptic NMDA receptors. Synaptic NMDA receptors of dentate gyrus neurons utilize glycine rather than D-serine as the co-agonist. �
Taken collectively, multilayered outcome measures show that L-aspartate doesn’t simply function as an agonist on NMDA receptors but also glycine and D-serine play fundamental roles in glutamatergic neurotransmission in the human brain. But, other molecules also have been demonstrated to be relevant modulators of glutamatergic neurotransmission. �
Glutamate Activated by Other Molecules
L-homocysteate (L-HCA) has structural similarities with L-glutamate. The non-protein amino acid is an oxidation product of homocysteine that is biosynthesized from methionine in the elimination of its own terminal methyl group and it is also an intermediate of the transsulfuration pathway by which methionine may be converted to cysteine through cystathionine. Early research studies demonstrated that this amino acid can cause calcium influx in cultured neurons as safely and effectively as L-glutamate. Moreover, L-HCA revealed an increased affinity for NMDA receptors when compared to other iGluRs in binding assays associated with its capacity to cause NMDA receptor antagonist-inhibitable excitotoxicity and sodium influx. Additionally, L-HCA can trigger mGluR5 as efficiently as L-glutamate. L-HCA is found in the brain, however, the concentrations were demonstrated to be approximately 500-fold lesser than those of L-glutamate and even 100-fold lesser when compared to those of L-aspartate in different regions of the rat brain. Throughout potassium-induced stimulation, L-HCA discharge is triggered from brain slice preparations as demonstrated for L-aspartate and L-glutamate although the absolute release of HCA is approximately 50-fold lesser. Surprisingly, HCA is a very efficient competitive inhibitor of cystine and L-glutamate uptake through the cystine/glutamate antiporter system x?c, the activity that regulates and manages the extracellular extrasynaptic L-glutamate concentrations in the brain. Therefore, the impact of L-HCA on the activation of NMDA and other L-glutamate receptors may also rely on the L-HCA-induced trigger of L-glutamate through system x?c. L-HCA may play an important role in the overall stimulation of L-glutamate receptors. Nevertheless, this can change tremendously under certain conditions, e.g., in patients with high-dose methotrexate therapy, an anticancer drug which, by restricting dihydrofolate reductase, limits the tetrahydrofolate-catalyzed recycling of methionine from homocysteine. Here, L-HCA concentrations of more than 100 ?M have been demonstrated from the cerebrospinal fluid whereas L-HCA was undetectable in control subjects. Further research studies are still required to determine these outcome measures. �
Further endogenous small molecules which are believed to affect L-glutamate signaling include several intermediates of tryptophan metabolism, as shown in Figure 2. Through the activity of indoleamine 2,3-dioxygenase (IDO) or tryptophan 2,3-dioxygenase (TDO), tryptophan is turned into N-formyl-L-kynurenine which is later turned into kynurenine (KYN) by formamidase. Three pathways, two of which connect at a subsequent step, result in further metabolism. First, through the activity of kynurenine aminotransferase (KAT), KYN is converted into kynurenic acid (KYNA). KYN can also be converted to 3-hydroxykynurenine (3HK) by kynurenine monooxygenase (KMO), which can subsequently be utilized as a substrate by kynureninase for the synthesis of 3-hydroxyanthranilic acid (3HANA). Additionally, utilizing KYN as a substrate, kynureninase develops anthranilic acid (ANA), which by non-specific hydroxylation may also be converted to 3HANA. According to research studies, 3HANA finally functions as a substrate for the generation of quinolinic acid (QUIN). �
The tryptophan concentration in the rat brain is roughly 25 nmol/g wet weight and approximately 400-fold less than L-glutamate and 100-fold less than L-aspartate. The demonstrated brain levels of kynurenines are even lower with 0.4-1.6 nmol/g for QUIN, 0.01-0.07 nmol/ml for KYNA, and 0.016 nmol/g for 3HANA. Approximately 40 percent of brain KYN is locally synthesized. The metabolites of tryptophan demonstrate differential binding to plasma proteins and their transport through the barrier which is quite different. KYN and 3HK are carried through the large neutral amino acid carrier system L. Kynurenines seem to penetrate the human brain by passive diffusion. Additionally, KYNA, 3HANA, and especially ANA bind to serum proteins which then ultimately restrict and limit their diffusibility across the blood-brain barrier. �
Research studies demonstrated that QUIN, when ionophoretically utilized in rat cells, caused neuronal firing which has been prevented by an NMDA receptor antagonist, suggesting that QUIN may function as an NMDA receptor agonist. However, the EC50 for QUIN to trigger NMDA receptor currents has been shown to be roughly 1000-fold higher than the EC50 of L-glutamate. Intracerebral injection of QUIN was proven to cause ultrastructural, neurochemical, and behavioral changes similar to those caused by NMDA receptor agonists. The fact that QUIN concentrations are about 5000- to 15,000-fold lower than cerebral L-glutamate concentrations makes it unlikely that modulation of NMDA receptor signaling by QUIN plays an essential role. KYNA was demonstrated to function as an NMDA receptor antagonist. But, although infusion with the KMO inhibitor Ro 61-8048 improved cerebral extracellular KYNA concentrations 10-fold, this didn’t result in an inhibition of NMDA-mediated neuronal depolarization, a finding which challenges the belief that KYNA at near-physiological amounts directly modulates NMDA receptors. In comparison, increased KYNA in the brain induced from the KMO inhibitor JM6 decreased the extracellular cerebral L-glutamate concentration. Additionally, KYNA levels from the extracellular cerebral fluid have been associated with L-glutamate levels suggesting that even at physiological or near physiological levels, KYNA modulates L-glutamate metabolism. Both the activation of the G-protein-coupled receptor GPR35 and the inhibition of presynaptic ?7 nicotinic acetylcholine receptors are suggested in the KYNA-induced reduction in L-glutamate release. To summarize, although QUIN and L-HCA are present in the human brain, their concentrations discuss against them with roles in regulating and maintaining neurotransmission. In contrast, even though the pathways have to be defined in greater detail, evidence supports levels and the opinion that discharge can be modulated by KYNA and neurotransmission. �
Glutamate, together with aspartate and other molecules, are several of the main excitatory neurotransmitters in the human brain. Although these play a fundamental role in the overall structure and function of the central nervous system, including the brain and the spinal cord, excessive amounts of other molecules can ultimately trigger glutamate receptors. Excess glutamate can cause excitotoxicity which may lead to a variety of health issues, such as Alzheimer’s disease and other types of neurological diseases. The following article describes how other molecules can activate glutamate receptors. – Dr. Alex Jimenez D.C., C.C.S.T. Insight – Dr. Alex Jimenez D.C., C.C.S.T. Insight
Research studies suggest that L-aspartate, like L-glutamate, triggers excitatory activity. L-aspartate functions with L-glutamate in the synaptic vesicles of asymmetric excitatory synapses. But, the total concentration of these in the human brain suggest that L-aspartate is significantly less abundant than L-glutamate. Moreover, L-aspartate is a powerful agonist for NMDA receptors but not for other iGluRs with an EC50 just eight-fold higher than that of L-glutamate. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. We use functional health protocols to treat injuries or chronic disorders of the musculoskeletal system. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Lewerenz, Jan, and Pamela Maher. �Chronic Glutamate Toxicity in Neurodegenerative Diseases-What Is the Evidence?� Frontiers in Neuroscience, Frontiers Media S.A., 16 Dec. 2015, www.ncbi.nlm.nih.gov/pmc/articles/PMC4679930/.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
�
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download �
* All of the above XYMOGEN policies remain strictly in force.
The term excitotoxicity was first employed to demonstrate the capability of L-glutamate, in addition to structurally-associated amino acids, to destroy nerve cells, a process which has been suggested to occur in acute and chronic health issues of the central nervous system (CNS). Excitotoxicity is caused by the excess stimulation of iGluRs into a characteristic loss of cell bodies and dendrites as well as post-synaptic structures. There is a substantial degree of variation in the sensitivity of nerve cells compared to the variety of iGluRs which is associated with the specific receptors demonstrated on the nerve cells and their metabolisms. The susceptibility of neurons to excitotoxicity can be affected with age. �
Acute excitotoxic nerve cell death is believed to occur in reaction to a number of severe insults, including cerebral ischemia, traumatic brain injury (TBI), hypoglycemia, and status epilepticus. However, what about neurodegenerative diseases, such as Alzheimer’s disease? Does chronic excitotoxicity also occur? Could exposure of nerve cells to low but above-average concentrations of L-glutamate, or even glutamatergic neurotransmission through a variety of molecules be involved as previously mentioned, within an extended time period also significantly result in neural cell death? The purpose of the article below is to demonstrate the concepts of acute and chronic glutamate toxicity on the health and wellness of the brain. �
Acute and Chronic Glutamate Toxicity
Excitotoxicity was initially studied in animals, however, so as to comprehend the mechanisms underlying this procedure, cell culture models were developed. The basic cell culture model of acute excitotoxicity involves the treatment of principal neurons in accordance with L-glutamate or particular iGluRs for a brief time interval (min) and then analyzing downstream events in the time point which is most relevant for the research study. By way of instance, cell death is frequently determined after 24 hours. While these types of research studies are proven to be quite useful for understanding the pathways involved in acute excitotoxicity, it has demonstrated to be far more difficult to evaluate chronic excitotoxicity in culture partially because it is not completely clear how to specify “chronic” in the context of cell culture. Does consistent imply a minimal dose supplied for 24 hours instead of a maximum dose supplied for 5 to 10 minutes or is it more complicated than that? �
Among the few research studies which tried to come up with a model of chronic excitotoxicity, it was revealed that it is indeed more complicated with acute and chronic excitotoxicity appearing to be different processes. In this research study, the researchers utilized pure cultures of primary cortical neurons developed from day 14 mouse embryos and treated them after seven and 14 days in culture (DIV). For constant excitotoxicity, the neurons were exposed to L-glutamate or NMDA for 24 hours and for severe excitotoxicity for 10 minutes. In both circumstances, cell death was measured after 24 hours. Surprisingly, the EC50s in their toxicity of L-glutamate were lower for acute toxicity, particularly in the 7 DIV cultures, when compared with the EC50s for chronic toxicity. Additionally, it was discovered that a high cell culture density increased the cells’ sensitivity into excitotoxicity that was acute but not chronic. Further research studies indicated that the lower sensitivity of these neurons to L-glutamate in the chronic excitotoxicity paradigm was due to the stimulation of mGluR1, associated with earlier data on the neuroprotective effects of mGluR1 stimulation, among other important processes. �
Further Research Studies for Glutamate Toxicity
An alternative approach for understanding chronic glutamate toxicity used organotypic spinal cord cultures in conjunction with L-glutamate uptake inhibitors. These spinal cord cultures, which had been prepared from 8-day-old rat pups, were kept in culture for up to 3 months. Persistent inhibition of L-glutamate uptake utilizing two varieties of uptake inhibitors caused a consistent increase of L-glutamate in the cell culture medium and time period as well as a concentration of dependent motor neuron cell death. The highest concentration of uptake inhibitor increased extracellular L-glutamate levels at least 25-fold and began to kill the cells within 1 week whereas a five-fold lower concentration raised extracellular L-glutamate levels eight-fold and cell death only began after 2 to 3 weeks of treatment. The toxicity was obstructed with non-NMDA but not NMDA receptors as well as by inhibitors of L-glutamate synthesis or release. These research studies ultimately indicate that moderately increased L-glutamate concentrations can also induce toxicity as well as a variety of other health issues. �
In vivo approaches to studying excitotoxicity have relied on an approach analogous to that utilized with the spinal cord cultures. In the wide variety of the research studies, a single or multiple EAATs were transiently or permanently genetically eliminated and the effects on brain function were evaluated. During the first few research studies, which utilized rats, chronic intraventricular administration of antisense RNA was utilized to eliminate every one of the 3 primary EAATs (EAAT1, EAAT2, and EAAT3). The loss of either of the glial L-glutamate transporters (EAAT1 and EAAT2) but not the neuronal transporter (EAAT3) caused large increases in extracellular L-glutamate concentrations in the striatum following 7 days as demonstrated by microdialysis (EAAT2, 32-fold increase; EAAT1, 13-fold increase). Treatment with the EAAT1 or EAAT2 antisense oligonucleotides caused a progressive motor impairment whereas epilepsy was produced by the EAAT3 antisense oligonucleotide. The loss of any of the 3 transporters demonstrated clear evidence of neuronal damage in the striatum and hippocampus after 7 days of treatment although the effects of the EAAT1 and EAAT2 antisense oligonucleotides were far more dramatic, consistent with the substantial increases in extracellular L-glutamate brought about by treatment. �
Particularly different results were demonstrated with homozygous mice deficient in EAAT2 or EAAT1. Mice deficient in EAAT2 demonstrated sudden and normally deadly seizures with 50 percent dead by 6 weeks of age. Approximately 30 percent of these mice demonstrated selective degeneration in the CA1 area at 4 to� 8 weeks of age. L-glutamate amounts in the CA1 region of the hippocampus measured by microdialysis were three-fold greater in the mutant mice as compared with the wild type mice. In contrast, heterozygous EAAT2 knock-out mice have an average lifespan and do not reveal hippocampal CA1 atrophy. However, they exhibit several behavioral abnormalities suggestive of moderate glutaminergic hyperactivity. While mice deficient in EAAT1, that is expressed in cerebellar astrocytes, didn’t reveal changes in cerebellar arrangement or obvious indicators of cerebellar impairment, such as ataxic gait, they had not been able to adapt to difficult motor tasks like rapidly running the rotorod. When taken collectively, these results imply that disruptions in homeostasis which are glutamatergic have a greater impact when they occur in the animal rather than when they are found from conception. �
Other Health Issues in Glutamate Toxicity
Tuberous sclerosis complex (TSC) is a multi-system genetic disease caused by the mutation of both TSC1 or TSC2 genes, where it is characterized by severe neurodegenerative diseases. Mice with inactivation of the TSC1 gene in glia have a less than 75 percent reduction in the expression and function of EAAT1 and EAAT2 as well as to cause seizures. At 4 weeks of age, prior to the development of seizures in these mice, there was a 50 percent increase in extracellular L-glutamate in the hippocampus of the mutant mice, as determined by microdialysis, which correlated with increases in markers of cell death in neurons in both hippocampus and cortex. Utilizing slices from mice that were 2 to 4 week old, impairments in long-term potentiation were determined, which translated into deficits when mice were analyzed for contextual and spatial memory in the Morris water maze and fear conditioning assays. Further research studies are still necessary for outcome measures. �
In the majority of the research studies described above, there was a large increase in extracellular L-glutamate that, when analyzed, caused adverse effects on the role of specific neuronal populations. To ascertain the long-term effects of more moderate increases in extracellular glutamate, further research studies created transgenic (Tg) mice with extra copies of this gene for Glud1, especially in neurons. Mitochondrial 2-oxoglutarate from Glud1 is transported into the cytoplasm of nerve terminals in which it’s converted back into L-glutamate and kept in synaptic vesicles thus leading to the pool of synaptically releasable L-glutamate. Nine-month-old Glud1 Tg mice demonstrated a 10 percent boost in L-glutamate in the hippocampus and striatum relative to wild type mice as determined to utilize magnetic resonance spectroscopy. In addition, 50 percent caused increased L-glutamate release in the striatum. At 12 to 20 months of age, the Glud1 Tg mice revealed significant decreases in the numbers of neurons in the CA1 area of the hippocampus and granule cell layer of the dentate gyrus in addition to an age-dependent loss of the two dendrites and dendritic spines in the hippocampus. There was also a drop in long-term potentiation after high frequency stimulation in hippocampal slices in the mice when compared with the wild type mice. Evaluation of the transcriptome of those Glud1 Tg mice in comparison with wild type mice indicated that long-term moderate increases in cerebral L-glutamate ultimately caused both rapid aging in the level of gene expression combined with compensatory reactions which protected against pressure and/or promoted recovery, among other capabilities. �
Conclusion
Brain function and nerve cell survival can be affected by excitotoxicity. The results appear to be highly dependent on the degree of L-glutamate increase, however, even a 10 percent growth appears to influence nerve cell survival, particularly in the context of aging indicating that chronic excitotoxicity may be associated with neurodegenerative diseases. �
Several toxins which connect to iGluRs and that have also been demonstrated to cause excitotoxicity in cell culture may cause slowly growing neurological health issues in both animals and humans. Surprisingly, each toxin appears to target a particular type of neuron, an effect which may be associated with the pharmacokinetics and ADME properties of the toxins, which have not been analyzed to any great extent. The data from these types of toxins supports the idea that excitotoxicity may play a fundamental role in neurodegenerative diseases as well as in other health issues which exist in humans. �
Because iGluRs are demonstrated both from the synapse and in extra-synaptic locations, there has been a great deal of effort devoted to discovering if the region of the receptors impacts the toxicity of molecules. An influential research study with primary neuronal cultures indicated that synaptic and extrasynaptic NMDA receptors have counteracting effects on cell survival with neural cell death being primarily controlled by extrasynaptic NMDA receptors. Nonetheless, these outcome measures have not been reproduced in brain slices or in vivo. Furthermore, many more recent research studies utilizing the exact same primary neuronal culture preparation protocol as the prior research study found either no difference between synaptic and extrasynaptic NMDA receptors in boosting excitotoxicity or discovered that both receptors were needed for cell death. Finally, a variety of research studies that supported the idea that extrasynaptic NMDA receptors promote excitotoxicity relied on the NMDA receptor inhibitor memantine that was originally believed to specifically act on extrasynaptic NMDA receptors. However, more recent research studies demonstrate that memantine can inhibit both synaptic and extrasynaptic NMDA receptors. These results strongly imply that synaptic and extrasynaptic NMDA receptors may contribute to excitotoxicity but the contribution of each depends on the experimental and/or pathological conditions. �
Glutamate is the primary excitatory neurotransmitter in the brain. Although it plays a fundamental role in the overall structure and function of the central nervous system, excessive amounts of glutamate can ultimately cause excitotoxicity which may lead to a variety of health issues, such as Alzheimer’s disease and other types of neurodegenerative diseases. Acute and chronic excitotoxicity treatment currently focuses on decreasing or restricting glutamate receptors or extracellular glutamate. The article above summarizes the available research studies for glutamate toxicity in neurodegenerative diseases. – Dr. Alex Jimenez D.C., C.C.S.T. Insight
Excitotoxicity demonstrates the capability of L-glutamate, as well as structurally-associated amino acids, processes which have been suggested to occur in acute and chronic excitotoxicity. Excitotoxicity is caused by the excess stimulation of iGluRs in cell bodies and dendrites as well as post-synaptic structures. There is a substantial degree of variation in nerve cells compared to iGluRs associated with the receptors demonstrated on the nerve cells and their metabolisms. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. We use functional health protocols to treat injuries or chronic disorders of the musculoskeletal system. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Lewerenz, Jan, and Pamela Maher. �Chronic Glutamate Toxicity in Neurodegenerative Diseases-What Is the Evidence?� Frontiers in Neuroscience, Frontiers Media S.A., 16 Dec. 2015, www.ncbi.nlm.nih.gov/pmc/articles/PMC4679930/.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
�
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited.
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download �
* All of the above XYMOGEN policies remain strictly in force.
L-glutamate is one of the main excitatory neurotransmitters in the human brain and it plays an essential role in practically all activities of the nervous system. In the following article, we will discuss the general principles of L-glutamate signaling in the brain. Then, we will demonstrate this scheme by describing the different pools of extracellular glutamate, including the synaptic, the perisynaptic, and the extrasynaptic, resulting from vesicular and non-vesicular sources or abnormally located glutamate receptors outside of synapses as well as discuss their possible physiological functions in the human brain. �
Glutamate Signaling in the Brain
According to research studies, the human brain has about a 6 to 7 ?mol/g wet weight of L-glutamate. L-glutamate, together with glutamine, is one of the most abundant free amino acids in the central nervous system (CNS). More than five decades ago, several research studies demonstrated that L-glutamate has an excitatory response on nerve cells. Since then, its role as an excitatory neurotransmitter as well as its cerebral metabolism has been evaluated in numerous research studies. �
L-glutamate is commonly found throughout synaptic vesicles in the presynaptic terminal through the process of vesicular glutamate transporters. Additionally, several of the L-glutamate in the vesicles may develop by a vesicle-associated aspartate amino-transferase from 2-oxoglutarate utilizing L-aspartate as the amino group donor. During the depolarization of the presynaptic membrane, L-glutamate is released into the synaptic cleft and connects to ionotropic glutamate receptors, known as iGluRs, at the postsynaptic membrane, as shown in Figure 1. According to research studies, iGluRs are characterized as ligand-gated ion channels which include receptors of the ?-amino-3-hydroxy-5-methyl-4-isoxazole propionic acid (AMPA), kainate, and N-methyl-D-aspartic acid (NMDA) types. While AMPA and kainate receptors primarily regulate and maintain sodium influx, NMDA receptors actually have a high calcium conductivity. Moreover, the activation of NMDA receptors plays a fundamental role in synaptic plasticity and learning. In contrast to the other iGluRs, the activity of NMDA receptors is ultimately restricted by an Mg+2 block at the regular membrane potential, however, the ion channel is immediately unblocked by membrane depolarization which eliminates Mg+2 from the pore. Furthermore, NMDA receptors are tetramers that have two NR1 subunits and two NR2 or NR3 subunits, according to several research studies. �
Additionally to iGluRs, there are also eight isoforms of metabotropic glutamate receptors (mGluRs) which belong to the family of G-protein-coupled receptors, where they don’t develop ion channels but instead signal through a variety of second messenger systems. L-glutamate-associated depolarization causes a postsynaptic excitatory potential which eases the development of an action potential at the axon hillock. The glutamatergic synapse is activated by astrocytic processes that demonstrate high levels of excitatory amino acid transporters (EAATs). There are five different EAATs, EAAT1 to 5, of which EAAT1 and 2 are the primary astrocytic EAATs, whereas EAAT3 shows a predominantly neuronal expression. Approximately 90 percent of the L-glutamate transport is regulated and maintained by EAAT2 such as GLT-1 in rodent models. These transporters then co-transport 2 or 3 molecules of Na+ and a proton with each molecule of L-glutamate or L-aspartate together with the counter-transport of a K+ ion. Therefore, by utilizing the electrochemical gradient of these ions throughout the plasma membrane as an energy source, the transporters are able to safely and effectively accumulate L-glutamate and L-aspartate in cells against their sudden intra- to extracellular concentration gradients. This allows the brain to control a very low extracellular L-glutamate concentration in the low micromolar range. It is generally believed that L-glutamate taken up by astrocytes is turned to glutamine by the enzyme glutamine synthetase, the glutamine is then released, taken up by neurons and turned to L-glutamate, where it is ultimately utilized once again for neurotransmission. �
Extrasynaptic Glutamate in the Brain
Aside from the essential role of L-glutamate as the primary excitatory neurotransmitter released from glutamatergic presynapses, as previously mentioned above, it has become evident that L-glutamate receptors outside the synaptic cleft also play an essential role in brain physiology. In the cerebellum, it was demonstrated by evaluating AMPA receptor-mediated currents in Bergmann glia that synaptically released L-glutamate concentrations can reach extrasynaptic concentrations of up to 190 ?M while concentrations in the synaptic cleft can exceed 1 mM. Moreover, several mGluRs have been shown to demonstrate a different localization in proximity to the postsynaptic density which would allow them to immediately recognize L-glutamate escaping from the synaptic cleft, as shown in Figure 1. However, current research studies have demonstrated that iGluRs, especially of the NMDA type, are also found at extrasynaptic regions in the neuronal cell membrane. Utilizing light and electron microscopy, other research studies also demonstrated that extrasynaptic NMDA receptors gather at different regions of close contact in the dendritic shaft with axons, axon terminals, or astrocytic processes. The proportion of extrasynaptic NMDA receptors was estimated to be as high as 36 percent of the dendritic NMDA receptor pool in rat hippocampal slices. Although extrasynaptic NMDA receptors were associated with similar scaffolding proteins as synaptic NMDA receptors, an in vitro research study suggested that extrasynaptic and synaptic NMDA receptors may ultimately activate different downstream signaling pathways with a variety of results, including the suppression of CREB activity by extrasynaptic NMDA receptor activation as well as activation by synaptic NMDA receptors. Furthermore, NMDA receptors localized extrasynaptically on dendritic shafts connect extrasynaptic L-glutamate as well as regulate and maintain Ca2+ influx during the elimination of the Mg+2 block by dendrite depolarization throughout the backfiring of action potentials. Research studies demonstrated that L-glutamate release from astrocytes can activate slow inward currents through extrasynaptic NMDAR receptors in CA1 neurons which can also be ultimately synchronized. The mechanisms through which glial cells release L-glutamate as well as how the extrasynaptic L-glutamate concentrations are controlled are vital towards understanding how the activity of extrasynaptic NMDA receptors is controlled. �
Different mechanisms through which astrocytes can release L-glutamate have been suggested, including vesicular L-glutamate release and non-vesicular release through anion channels as well as connexin hemichannels and release through the cystine/glutamate antiporter system x?c. Several research studies strongly suggest that vesicular release from astrocytes plays a minor role because the Ca+2-associated release of L-glutamate was still present in astrocytes created from dominant-negative SNARE mice where vesicular release can be blocked by doxycycline withdrawal. System x?c is a cystine/glutamate antiporter which is characterized as heterodimeric amino acid transporters, made up of xCT as the specific subunit and 4F2hc as the promiscuous heavy chain. This transporter is demonstrated in the brain, especially in astroglial and microglial cells, as shown in Figure 1. The fact that extrasynaptic L-glutamate levels in different regions of the human brain are downregulated by approximately 60 percent to 70 percent in xCT knock out mice, research studies demonstrated that system x?c releases L-glutamate into the extrasynaptic space and suggests that this transporter is essential in the regulation of extrasynaptic L-glutamate levels. This is further supported by the observation that when measured by in vivo microdialysis, the increase in extrasynaptic L-glutamate developed by EAAT inhibitors is neutralized by blocking system x?c while blocking neuronal vesicular L-glutamate release is ineffective. Further research studies are still required. �
Taken together, glutamatergic neurotransmissions don’t simply happen through classical excitatory synapses but also through extrasynaptic L-glutamate receptors, as shown in Figure 1. Finally, the levels of extrasynaptic L-glutamate are determined, at least partially, by glial non-vesicular L-glutamate release, as also shown in Figure 1. However, the regulation of extrasynaptic L-glutamate levels, as well as its temporal-spatial dynamics and its effect on neuronal function, neurodegeneration, and behavior, are far from being fully understood by researchers, healthcare professionals, and patients. �
Glutamate, together with aspartate, is one of the main excitatory neurotransmitters in the human brain. Although it plays a fundamental role in the overall structure and function of the nervous system, excessive amounts of glutamate can ultimately cause excitotoxicity which may lead to a variety of health issues, such as Alzheimer’s disease and other types of neurological diseases. The following article describes the role of glutamate in the human brain. – Dr. Alex Jimenez D.C., C.C.S.T. Insight
L-glutamate is one of the main excitatory neurotransmitters in the human brain and it plays an essential role in practically all activities of the nervous system. In the article above, we discussed the general principles of L-glutamate signaling in the brain. Then, we demonstrated this scheme by describing the different pools of extracellular glutamate, including the synaptic, the perisynaptic, and the extrasynaptic, resulting from vesicular and non-vesicular sources or abnormally located glutamate receptors outside of synapses as well as discussed their possible physiological functions in the human brain. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. We use functional health protocols to treat injuries or chronic disorders of the musculoskeletal system. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Lewerenz, Jan, and Pamela Maher. �Chronic Glutamate Toxicity in Neurodegenerative Diseases-What Is the Evidence?� Frontiers in Neuroscience, Frontiers Media S.A., 16 Dec. 2015, www.ncbi.nlm.nih.gov/pmc/articles/PMC4679930/.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
�
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited.
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download �
* All of the above XYMOGEN policies remain strictly in force.
For people who love drinking diet sodas, recent research studies have found that diet drinks can increase the risk of stroke and dementia. Although diet drinks have been previously advertised as a much more healthier, low-calorie alternative than regular carbonated drinks, a closer look at the results of these recent research studies ultimately suggests otherwise. �
One research study, consisting of 2,888 participants, ages 45 and older, in the Framingham Heart Study, asked for diet entries to be filled out up to three times within a seven-year period. According to the research study, participants who said they drank one diet soda a day were roughly twice as likely to have a stroke within the next decade than individuals who didn’t drink diet soda. Drinking regular, sugar-sweetened carbonated drinks did not seem to increase the risk of stroke. �
However, these types of research studies have only been able to prove an association between diet drinks, stroke, and dementia. “Also, only 97 people (about 3 percent) had strokes during the follow-up, which means that only two or even three of those strokes may be associated to drinking diet soda,” stated Dr. Kathryn Rexrode, an associate professor of medicine at Harvard-affiliated Brigham and Women’s Hospital which co-authored a research study on soda intake and stroke risk. �
Risk of Stroke Associated with Diet Drinks
The research study found a slightly increased risk of stroke in people who drank more than one soda per day, whether or not it contained any type of artificial sweetener. Although the research study didn’t particularly show a considerable increase in stroke risk, that doesn’t necessarily suggest that they’re a better option than diet sodas. Research studies have shown that drinking carbonated drinks may lead to weight gain, diabetes, high blood pressure, heart disease, and stroke, ” she stated. �
As a matter of fact, researchers believe that one possible explanation as to why regular, sugar-sweetened carbonated drinks weren’t associated with stroke in the recent research study is a phenomenon known as the survival bias. In this instance, it would mean that individuals who drink a lot of carbonated drinks may have died from health issues such as heart disease. �
Conversely, diet drinks may be associated with an increased risk of stroke due to a variety of health issues known as reverse causation. In an attempt to be healthier, individuals who are overweight or have diabetes may be more inclined to select diet drinks over regular drinks. Their increased risk of stroke may come from their health issues rather than their drink option. “We may ultimately only be measuring the residual effect of weight gain, obesity, and diabetes,” says Dr. Rexrode. �
Artificial Sweeteners and Stroke
� Although researchers need further evidence to determine why artificial sweeteners may increase stroke risk, there are other reasons as to why these should be avoided. Research studies show that artificial sweeteners can make individuals crave sugary, high-calorie meals, therefore, decreasing the artificial sweetener’s purpose of cutting your total calorie consumption. �
Moreover, many researchers believe that people who use these artificial sweeteners, which can be many times sweeter than sugar, can come to find naturally sweet foods, such as fruits, to be less appealing and less-sweet foods, such as vegetables, to be entirely unpalatable. Furthermore, individuals may be missing out on the many nutrients found in fresh, natural foods. �
“I encourage my patients to stop drinking soda and other sugar-sweetened carbonated drinks regularly to prevent empty calories,” she says. “However, if someone says that they can’t do without soda in the morning to wake up, I will encourage them to switch to diet soda.” Water is a much better choice, however. “There are plenty of ways to make it more attractive, both visually and taste-wise.” She adds. Try flavoring sparkling or flat water or add crushed mint, cucumber, or frozen fruit. �
Risk of Dementia Associated with Diet Drinks
In another research study, people who drank diet soda were associated with an increased risk of developing dementia. “The research study can’t prove a connection between drinking habits and health issues, however, it does strongly suggest an association,” Stated Dr. Matthew Pase, neurology fellow at Boston University School of Medicine and contributing author. �
The initial research study evaluated food questionnaires, MRI scans, and cognitive tests of approximately 4,000 people ages 30 and up. Researchers found that individuals who consumed over three diet sodas per week were more likely to have memory problems, a reduced brain volume, and a smaller hippocampus, an area of the brain used in memory and learning. In the research study, drinking a minimum of one diet soda per day was also associated with a reduced brain volume. �
During a second research study, the researchers tracked two different groups of adults for ten years. According to the research study, out of almost 3,000 adults over age 45, approximately 97 adults suffered a stroke during that time and from almost 1,500 adults over age 60, approximately 81 adults developed Alzheimer’s disease or another type of dementia. �
Past research studies have connected diet drinks to an increased risk of weight gain and stroke. Researchers believe that artificial sweeteners may ultimately affect the human body in many different ways, such as by transforming gut bacteria and tricking the brain into craving more calories. This is the first-time diet sodas have been associated with dementia. Because people with diabetes drink more diet soda, researchers believe that the health issue may partly explain the rise in dementia, although not completely. When people with diabetes were excluded from the research study, the association stayed. �
As stated by the United States Department of Agriculture, Americans consumed 11 million metric tons of sugar in 2016, much of it in the form of sugary, sweetened carbonated drinks. Because it would have been difficult to measure total sugar consumption from all type of different food sources, the research study focused on sugary, sweetened carbonated drinks. �
A growing number of research studies suggest that diet drinks may not be a safe alternative to sugary, sweetened drinks. Even small causal effects can have much bigger consequences on health, given the popularity of both diet and regular sodas. The research study concluded that both glucose and artificially sweetened soft drinks “may be hard on the brain.” �
Diet soda is basically a mixture of carbonated water, natural or artificial sweetener, colors, flavors, and other food additives. Although diet drinks generally have very few to no calories, these essentially have no significant nutritional value. Many research studies have demonstrated that drinking diet soda is associated with an increased risk of stroke and dementia. Researchers have also found that diet drinks can cause a variety of other health issues. It’s essential for to avoid drinking too much diet soda. – Dr. Alex Jimenez D.C., C.C.S.T. Insight
Recent research studies have found that diet drinks are associated with an increased risk of stroke and dementia. Although diet drinks are advertised as a much more healthier, low-calorie alternative than regular carbonated drinks, a closer look at the results of these recent research studies ultimately suggests otherwise. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Corliss, Julie. �Does Drinking Diet Soda Raise the Risk of a Stroke?� Harvard Health Blog, 31 July 2017, www.health.harvard.edu/blog/drinking-diet-soda-raise-risk-stroke-2017073112109.
MacMillan, Amanda. �A Daily Diet Soda Habit May Be Linked to Dementia.� Health.com, 21 Apr. 2017, www.health.com/alzheimers/diet-soda-linked-to-dementia-stroke.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited.
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download�
* All of the above XYMOGEN policies remain strictly in force.
Excitotoxicity is a pathological mechanism seen in a variety of health issues where an excessive synaptic excitation causes neuronal death and is also believed to be caused by the extracellular accumulation of the excitatory neurotransmitter glutamate, which triggers and connects ionotropic N-methyl-D-aspartate glutamatergic receptors (NMDARs) in the brain. Generally, NMDARs regulate and maintain calcium in cells to help manage physiological mechanisms like synaptic plasticity and memory, however, excessive stimulation can ultimately increase intracellular calcium which triggers cell death signaling to activate apoptosis. This pathological mechanism has been suggested in a variety of health issues, such as traumatic brain injury (TBI) and Alzheimer’s disease (AD), where it is extensively examined to understand health issues and treatment approaches. In a stroke, excitotoxicity has been shown to be the main pathological mechanism where neuronal damage happens and it is considered to be a well-known goal for many recent attempts at developing stroke therapeutics. �
Stroke is an acute brain health issue which causes neuronal damage which has currently no safe and effective neuroprotective treatment approaches. Immediately following a stroke, the brain tissue loses blood perfusion and the center of the infarct deteriorates quickly. This then causes milder ischemia and many brain cells or neurons will result in delayed death which can take up to several hours or even days. Research studies show that the mechanism of cell death is mainly NMDA receptor-dependent excitotoxicity. In ischemic areas, extracellular glutamate levels increase while preventing glutamate release, synaptic activity, or NMDAR activation which was capable of limiting cell death in a variety of stroke models. Thus, preventing excitotoxicity is an important treatment approach for reducing brain damage and improving patient outcome measures following a stroke, and this has definitely encouraged extensive efforts towards developing NMDA receptor-based stroke treatment approaches over the last two decades. Unfortunately, these have largely met with rather disappointing results. Several research studies have failed to find the expected efficiency of NMDAR for decreasing brain injuries. The reasons behind the basic research study results and clinical trials are still unknown, however, several reasons have been suggested. These include, but are not limited to, the inability to utilize the correct doses necessary for neuroprotection due to their side-effects, the inability to use the drugs within their neuroprotective windows, poor experimental designs, and heterogeneity in the patient population. However, as we will briefly summarize in the following article, improvement in our understanding of the physiological and pathological mechanisms of NMDAR activation as well as the different pathways connected to different NMDAR subtypes, has allowed researchers to develop new treatment approaches which improve therapeutic windows and increase specificity for death signaling pathways, achieving neuroprotection without interrupting other essential signaling pathways downstream of the NMDAR receptor. �
Neuroprotectants Targeting NMDAR Subtypes
NMDAR subtypes have different purposes in excitotoxicity and physiology. The NMDAR is a receptor which generally has two GluN1, also known as NR1, subunits as well as two subunits from the GluN2 subfamily (GluN2A-2D, also known as NR2A-2D). In the cortex, the major subpopulations of NMDARs are GluN2A- or GluN2A and 2B-containing receptors. GluN2A-containing receptors are found in synapses whereas GluN2B-containing receptors are found on extrasynaptic membranes. GluN2A- and GluN2B-containing receptors are different from each other because they regulate and manage plasticity, favoring either long-term potentiation (GluN2A) or depression (GluN2B) through a variety of electrophysiological and pharmacological properties as well as signaling proteins. In addition, these receptors play a fundamental role in promoting cell survival (GluN2A) or death (GluN2B) after excitotoxic stimulation. Because GluN2A-containing receptors are mainly focused on synapses while GluN2B-containing receptors are focused to both synaptic and extrasynaptic membranes, when excitotoxic conditions cause glutamate to extend beyond synapses, GluN2B-mediated death signaling becomes stronger in comparison to survival signaling which ultimately results in death. Through a stroke, by way of instance, NMDARs are less likely to favor cell survival and can instead cause detrimental effects by preventing considerable normal physiological purposes. Selfotel, a non-specific NMDAR blocker, was neuroprotective against stroke in vitro and in vivo, however, it ultimately failed to be neuroprotective against stroke in clinical trials by causing a variety of intolerable side-effects. �
Treatment strategies to reduce undesirable side-effects, including glycine site antagonists and NMDAR subtype-specific improvements, was to target the allosteric glycine binding regions on the GluN1 subunits with licostinel and gavestinel instead of directly blocking the receptor. These drug candidates performed well in preclinical examinations, however, they also failed as a result of low efficiency despite minimal side-effect profiles. The negative side-effects were perhaps due to a missed window of time following a stroke that shows which receptor blockers are safe and effective in preventing death. �
Better treatment methods and techniques for reducing unwanted side-effects of NMDAR are to utilize the differences between their variations. By way of instance, the GluN2B-specific inhibitor traxoprodil is neuroprotective in stroke research studies and minimal side-effects, however, it has also failed in clinical trials. Similar to the glycine region antagonists, it possibly needs to be properly regulated and managed to function efficiently. GluN2A agonists should promote cell survival signaling which could allow recovery following a stroke as well as cell survival to prevent passing signaling. As a matter of fact, activation of GluN2A-containing receptors utilizing increased doses of glycine was neuroprotective in an animal model of stroke but further research studies must examine GluN2A activation as a treatment approach in human participants. �
While NMDAR antagonists and modulators are safe and effective at attenuating excitotoxicity in experimental versions, their shortcoming is the challenge in implementing treatment approaches early to coincide with the summit of excitotoxic glutamate release. Stroke patients frequently have no chance of receiving these treatment approaches in time. However, the health issue can be avoided if receptor blockers can be utilized in at-risk populations. One research study has shown that low doses of prophylactic memantine, an NMDAR non-competitive antagonist with few side-effects, can considerably decrease brain injury and functional deficits following a stroke. Whether any medications are tolerable, safe, and effective when taken this way remains to be demonstrated but innovative solutions may nevertheless address how to deliver those drugs. �
One factor apart from those of the failed clinical trials is the interplay of NMDARs in cell survival which may be completely misunderstood. In the last few decades, there has been accumulating evidence that synaptic NMDARs may also cause cell death and GluN2A, as well as GluN2B, do not necessarily have dichotomous functions in excitotoxicity. Further research studies may be required to demonstrate more nuanced receptor inhibitor strategies and to solve this controversy. �
Neuroprotectants Targeting Cell Death Signaling
A treatment approach for NMDAR inhibitors is to focus on the most downstream events for cell death which happen over a much longer time period following receptor activation. A variety of cell death pathways following activation have been determined and several groups have provided proof-of-principle evidence that these pathways can be regulated and managed with the utilization of peptides to ultimately protect brain cells or neurons without any side-effects. �
The oldest reported and most explored peptide strategy in stroke goals is nitrous oxide synthase (nNOS)-mediated cell death. NNOS connects to postsynaptic protein 95 (PSD95) which then connects to the C-terminal tail of the GluN2B subunit. NOS is a calcium-activated enzyme which activates the development of nitric oxide (NO) and its own status in the receptor complex which associates it in proximity to the focused stream of calcium entering activated GluN2B. In a stroke, the excessive calcium influx activates GluN2B-coupled nNOS. An interference peptide is utilized to disconnect the complex to prevent NO development. The peptide, Tat-NR2B9c, is made up of an HIV-1 Tat-derived cell penetration sequence which allows passage through the blood-brain barrier and cell membranes, connected to a copy of the region on the GluN2B for PSD95. The peptide and GluN2B disconnect PSD95, therefore, decoupling nNOS in the local considerable levels of calcium without interrupting the function of the receptor from different pathways. Utilization results in considerable protection against tissue and functional damage with no side-effects in vitro and in vivo after a single dose given before or after ischemia in vivo. The peptide has lately succeeded in Phase II clinical trial where it decreased iatrogenic infarcts during intracranial aneurysm treatment. This is the first time a research study has demonstrated efficiency in humans which also shows authenticity that targeting downstream cell death can be helpful against excitotoxic/ischemic neuronal injuries. �
While the utilization of peptides in a clinical setting is safe and effective, a similar efficiency has been achieved with small molecule drugs which act on the exact same goal and function like the peptides in a laboratory setting. To mimic Tat-NR2B9c, two small molecules, IC87201 and ZL006 have been individually demonstrated to compete at the identical GluN2B-specific connecting region without affecting the connection of PSD95 to other proteins. Additionally, ZL006 imitates the peptide’s neuroprotection without causing any considerable adverse side-effects. By identifying the goals and the specific regions, research studies can simulate small molecule drugs and accelerate their discovery towards excitotoxicity and stroke. �
Other GluN2B-specific pathways have been demonstrated in a similar manner and are showing promise in the stages of development. One such pathway which is triggered following GluN2B activation is the potentiation and recruiting of GluN2B in the cell membrane by death-associated protein kinase 1 (DAPK1). DAPK1 is a protein which connects to calmodulin to activate apoptosis but it is phosphorylated in an inactive form which is incapable of associating cell death and calmodulin. Following excitotoxicity, calcineurin activation dephosphorylates and triggers DAPK1, contributing to cell death. Furthermore, active DAPK1 can connect to and phosphorylate the C-terminal tail of receptors, excitotoxicity, and their function, aggravating calcium influx. A Tat-linked interference peptide which has the C-tail phosphorylation region which is GluN2B managed to block the interaction of active DAPK1 with GluN2B and promote excitotoxicity. Once the peptide was utilized in mice, dubbed Tat-NR2B-CT, it improved the outcome following ischemia. However, Tat-NR2B-CT was only efficient at preventing activity and runaway insertion instead of the downstream apoptotic of DAPK1 signaling. Researchers were also able to connect and guide DAPK1 towards lysosomes by including a sequence in the close of the hindrance peptide to create a degradation peptide. The result has been a serious and temporary fall in busy DAPK1 levels with a corresponding decrease in infarction when administering the peptide hours after ischemia, according to several research studies. �
The c-Jun N-terminal kinase 3 (JNK) acts upon many pathways and is a mediator for cell death in excitotoxicity. JNK interacting protein (JIP) connects and prevents JNK activity through a JNK binding domain (JBD) which spans over 20 residues. When these residues are connected to Tat as from the Tat-JBD20 interrupted peptide, they are capable of limiting JNK activity and preventing cell death in stroke models when administered before or after ischemia. The Tat-JBD20 peptide has also been shown utilizing D-amino acids instead of L-amino acids to withstand degradation by endogenous proteases. Doing so tremendously increases the peptide’s half-life and doesn’t negatively affect its binding affinity and selectivity, demonstrating that this alteration may be utilized for several interference peptides to boost efficiency and bioavailability. �
New targets are always being discovered. While currently, no new stroke treatment approaches are being utilized, a great deal of progress has been made by targeting the processes which occur during stroke towards creating treatment approaches. With the debut of the achievement of degradation and interruption peptides targeting GluN2B-specific passing signaling events, there’s hope that new treatments are on the horizon for health issues which have excitotoxicity. �
Excitotoxicity is the pathological mechanism by which brain cells or neurons are ultimately damaged or eliminated by excessive stimulation from neurotransmitters, including glutamate and other similar substances. This ultimately occurs when the NMDA receptor and the AMPA receptor are overactivated by excitatory neurotransmitter glutamate receptors. This can cause a variety of processes which can damage cell structures, including components of the cytoskeleton, membrane, and DNA. Regulating and managing excitotoxicity can help maintain overall well-being. – Dr. Alex Jimenez D.C., C.C.S.T. Insight
Excitotoxicity is a pathological mechanism where an excessive synaptic excitation causes neuronal death and is also believed to be caused by the extracellular accumulation of the excitatory neurotransmitter glutamate, which triggers and connects ionotropic N-methyl-D-aspartate glutamatergic receptors (NMDARs) in the brain. This pathological mechanism has been suggested in a variety of health issues, such as traumatic brain injury (TBI) and Alzheimer’s disease (AD), where it is extensively examined to understand health issues and treatment approaches. The scope of our information is limited to chiropractic, musculoskeletal and nervous health issues as well as functional medicine articles, topics, and discussions. To further discuss the subject matter above, please feel free to ask Dr. Alex Jimenez or contact us at 915-850-0900 . �
Curated by Dr. Alex Jimenez �
References �
Li, Victor, and Yu Tian Wang. �Molecular Mechanisms of NMDA Receptor-Mediated Excitotoxicity: Implications for Neuroprotective Therapeutics for Stroke.� Neural Regeneration Research, Medknow Publications & Media Pvt Ltd, Nov. 2016, www.ncbi.nlm.nih.gov/pmc/articles/PMC5204222/.
Additional Topic Discussion: Chronic Pain
Sudden pain is a natural response of the nervous system which helps to demonstrate possible injury. By way of instance, pain signals travel from an injured region through the nerves and spinal cord to the brain. Pain is generally less severe as the injury heals, however, chronic pain is different than the average type of pain. With chronic pain, the human body will continue sending pain signals to the brain, regardless if the injury has healed. Chronic pain can last for several weeks to even several years. Chronic pain can tremendously affect a patient’s mobility and it can reduce flexibility, strength, and endurance.
Neural Zoomer Plus for Neurological Disease
�
Dr. Alex Jimenez utilizes a series of tests to help evaluate neurological diseases. The Neural ZoomerTM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural ZoomerTM Plus is designed to assess an individual�s reactivity to 48 neurological antigens with connections to a variety of neurologically related diseases. The Vibrant Neural ZoomerTM Plus aims to reduce neurological conditions by empowering patients and physicians with a vital resource for early risk detection and an enhanced focus on personalized primary prevention. �
Formulas for Methylation Support
XYMOGEN�s Exclusive Professional Formulas are available through select licensed health care professionals. The internet sale and discounting of XYMOGEN formulas are strictly prohibited.
Proudly,�Dr. Alexander Jimenez makes XYMOGEN formulas available only to patients under our care.
Please call our office in order for us to assign a doctor consultation for immediate access.
If you are a patient of Injury Medical & Chiropractic�Clinic, you may inquire about XYMOGEN by calling 915-850-0900.
�
For your convenience and review of the XYMOGEN products please review the following link.*XYMOGEN-Catalog-Download �
* All of the above XYMOGEN policies remain strictly in force.
IFM's Find A Practitioner tool is the largest referral network in Functional Medicine, created to help patients locate Functional Medicine practitioners anywhere in the world. IFM Certified Practitioners are listed first in the search results, given their extensive education in Functional Medicine
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