Functional Neurology: Chronic Excitotoxicity in Neurodegenerative Diseases Part 3

by Dr Alex Jimenez | Nerve Injury, Neuropathy

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. �

Huntington’s Disease

Huntington’s disease (HD) is as an inherited, fatal neurodegenerative disease which is caused by a trinucleotide (CAG) repeat expansion in the coding region of the huntingtin (htt) gene which is associated with the degeneration of the GABAergic medium-sized spiny neurons (MSN) in the striatum, although other brain regions can also ultimately be affected as the health issue progresses. HD is identified as a movement disorder with co-morbid cognitive and psychiatric symptomatology. Both mutant htt RNA together with the encoded protein which includes a polyglutamine repeat expansion is believed to cause the complicated changes in cellular metabolism which occurs in mitochondrial dysfunction and oxidative stress. �

Early research study findings which demonstrated that excitotoxicity may play a fundamental role in HD were based upon the observation that an injection of their KYN metabolite and NMDA receptor agonist QUIN, in addition to L-glutamate and kainate, in the striatum of rats caused neuronal degeneration. Another research study determined that QUIN, as compared to NMDA and kainate, causes selective degeneration of the MSNs instead of neuronal death, which tremendously resembles the pathology of HD. Moreover, NMDA receptors have been shown to be hyperactive and striatal neurons from different HD mouse models, such as a yeast artificial chromosome (YAC) which leads to over-expression of full-length htt with elongated polyglutamine repeats as well as R6/2 mice over-expressing htt exon 1 with elongated polyglutamine repeats in addition to in knock-in mice with greater CAG repeats inserted from the mouse htt gene, were demonstrated to be sensitized to excitotoxicity in vitro. Furthermore, in vivo, a sensitization to an excitotoxin injection into the striatum was only demonstrated in the transgenic YAC model of HD, whereas mice overexpressing mutant htt exon 1, R6/1 and R6/2 mice, or N171-82Q mice overexpressing mutant exon 1 and components of exon 2 or the so-called “shortstop” mouse expressing human N-terminal htt encoded by exon 1 and 2 with a 128 CAG repeat below the htt promoter, produced somewhat of a resistance to striatal excitotoxin injection during the aging process. This neuroprotection isn’t necessarily for NMDA receptor agonists, however, it can help different neurotoxic insults and may be an adaptive response to cellular stress. �

Rat MSN release increased levels of NR2A- and NR2B-containing NMDA receptors compared to interneurons in the striatum. NR1 and NR2B mRNA expression in the neostriatum of HD patients has been demonstrated to considerably decrease which is associated with the loss of these neurons. In addition, NMDA receptor-mediated pathways in MSN were determined to be tremendously sensitive to the NR2B-specific inhibitor ifenprodil. In HEK293 cells, overexpression of mutant htt increased NMDA receptor-mediated pathways and aggravated NMDA-induced cell release only when NR2B- but not when NR2A-containing NMDA receptors were co-expressed. One possible explanation for the increase in NR2B-containing NMDA receptor expression from HD models is that an extended polyglutamine repeat in htt decreases its connection to PSD95, a postsynaptic density protein included in NMDA and kainate receptor clustering, ultimately causing a greater response of PSD95 together with the NR2B subunit. Recently, research study findings suggest that not only does the subunit composition but also the localization of NMDA receptors may play a fundamental role in the NMDA receptor activity. Another research study showed that in severe striatal slice preparations from YAC transgenic mice utilizing 128 CAG repeats, extrasynaptic NMDA receptors, especially those with NR2B, are considerably increased compared to pieces from wild-type mice and YAC mice expressing htt with 18 CAG repeats. As expected from in vitro research studies, this change was associated with decreased CREB phosphorylation. The increased percentage of NR2B-containing extrasynaptic NMDA receptors was demonstrated to be associated with increased extrasynaptic localization of PSD95. One pathway which may cause the sensitization to excitotoxic stimulation downstream of the activation of extrasynaptic NMDA receptors was identified as activation of p38 MAPK. Taken multilayered evidence suggests that mutant htt results in sensitization of MSN into glutamate excitotoxicity through the redistribution of NMDA receptors from subunits to extrasynaptic sites. �

The activation of extrasynaptic NMDA receptors in acute striatal brain slices can be effectively shown in YAC mice utilizing 128 CAG repeats through spillover of synaptic glutamate by restricting EAATs. As a result, it may be determined that decreased EAAT expression may increase the activation of NMDA receptors. Surprisingly, within situ-hybridization, research studies discovered a decrease in astrocytic EAAT2 mRNA expression in the neostriatum of all HD patients. As compared to wild-type mice, however, no changes in protein expression were found to be decreased in synaptosomes of YAC mice overexpressing human htt utilizing 128 CAG repeats. The researchers determined that a decrease in EAAT2 activity from the YAC model of HD was caused by decreased palmitoylation of the transporter. In R6/2 mice, others discovered decreased EAAT2 mRNA and protein expression associated with decreased EAAT2 in synaptosomes or acute cortico-striatal pieces. However, extracellular striatal glutamate concentrations have been shown to be similar to those of wild-type control mice and a decreased glutamate clearance capability in the R6/2 mice demonstrated by therapy with EAAT inhibitors or glutamate. A putative explanation for this finding could be a decrease in glutamate release through system x?c and in xCT, the subunit of system x?c which has been demonstrated at the striatum of R6/2 mice in the mRNA and protein levels. �

As previously mentioned, the injection of the KYN metabolite QUIN in supraphysiological concentrations was utilized as an early animal model of HD. This caused further research studies of KYN metabolism in HD. Surprisingly, the QUIN precursor 3HK aggravates neurodegeneration from the QUIN HD version while KYNA is protective. Research studies discovered that in early-stage HD, compared to control and end-stage HD, neostriatal 3HK and QUIN concentrations were considerably upregulated. Another research study discovered that KYNA levels decreased in autopsied HD striata with the CSF of HD patients when compared with controls. The first enzyme of this KYN pathway, IDO, is triggered from the striatum of both YAC mice with 128 CAG repeats. Mice deficient in IDO are less sensitive to intrastriatal QUIN injection. Evaluation of KYN metabolites from three different mouse models of HD, R6/2 mice, YAC128 mice as well as HdhQ92 and HdhQ111 knock-in mice in various brain regions, suggested age-dependent activation of their KYN pathway. However, the detailed pattern of metabolite changes was different among the versions with increased 3HK in cortex, striatum, and cerebellum in R6/2 mice whereas mice expressing full-size mutant htt demonstrated an extra cortical and striatal upregulation of QUIN. Moreover, treatment of R6/2 mice with a non-blood brain barrier permeable KMO inhibitor, JM6, which indirectly improved cerebral extracellular KYNA concentrations by 50 percent, has been associated with a decrease in extracellular cerebral L-glutamate, decreased neurodegeneration and prolonged survival. Further research studies are still required for further evidence. �

Taken collectively, the research studies support the view that in HD there is a redistribution of both NMDA receptors, especially those containing NR2B, which can activate signaling pathways which boost neurodegeneration, as shown in Figure 5. There is not any evidence that cerebral L-glutamate levels are grossly increased in HD. This might be explained by the fact that even though EAAT2 and KYNA may be downregulated, there is also a downregulation of system x?c action. As only very high levels of QUIN activated NMDA receptors, this KYN metabolite is unlikely to contribute to the excitotoxic load. �

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

[wp-embedder-pack width=”100%” height=”1050px” download=”all” download-text=”” attachment_id=”72423″ /] � 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. �

In honor of Governor Abbott’s proclamation, October is Chiropractic Health Month. Learn more about the proposal. �

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

1. 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 Zoomer^TM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural Zoomer^TM 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 Zoomer^TM 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.

�

Functional Neurology: Chronic Excitotoxicity in Neurodegenerative Diseases Part 2

by Dr Alex Jimenez | Nerve Injury, Neuropathy

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. �

Alzheimer’s Disease

Alzheimer’s disease (AD) is one of the main causes of dementia among older adults in the United States. Neuropathologically, AD is characterized as neurodegeneration with extracellular senile plaques made up of ? amyloid (A?) and intraneuronal neurofibrillary tangles of aggregated tau, which initially appear in the hippocampus than then spread as the health issue progresses. Prominent microglial cell activation can also be associated with AD. Hereditary types of AD occur due to mutations in the A? precursor protein, A?PP, or in the presenilins, which are part of the multi-protein complex involved in A? generation. The pathophysiology of AD is complicated and a variety of pathways are included in the synaptic and the cellular degeneration in AD, such as abnormalities in signaling pathways through glycogen synthase kinase-3 beta or mitogen-activated protein kinases, cell cycle re-entry, oxidative stress, or decreased transport of trophic factors and adrenal dysregulation. However, evidence suggests that L-glutamate dysregulation plays a critical role in Alzheimer’s disease. �

Research studies demonstrated that primary neurons from transgenic mice overexpressing mutant presenilin are far more sensitive to excitotoxic stimulation in vitro. In vitro, aggregated A? increases both NMDA and kainate receptor-mediated L-glutamate toxicity, perhaps by interrupting neuronal calcium homeostasis. Others have demonstrated that A? can increase neuronal excitability by changing the capacity of glycogen synthase kinase 3? inhibition to decrease NMDA receptor-mediated pathways. Soluble A? oligomers were demonstrated to cause L-glutamate release from astrocytes resulting in dendritic spine loss through over-activation of extrasynaptic NMDA receptors. Moreover, extracellular L-glutamate concentrations were demonstrated to increase in a triple transgenic mouse model of AD, in which a 3-month treatment with the NMDA receptor inhibitor ultimately affected synapse loss. However, further research studies are still required. �

Numerous mouse research studies have demonstrated the consequences of AD-like pathology on EAAT expression and/or function. In acute hippocampal slice preparations, A? was shown to interrupt the clearance of synaptically released L-glutamate by diminishing membrane insertion of EAAT2, a result perhaps mediated by oxidative stress. In aged A?PP23 mice, research studies revealed the downregulation of EAAT2 expression in the frontal cortex and hippocampus, which in the frontal cortex was associated with an increase in xCT expression. These changes were associated with a strong tendency toward improved extracellular L-glutamate amounts as measured by microdialysis. In triple transgenic AD mice expressing the amyloid precursor protein mutations K670N and M671L, the presenilin 1 mutation M146V and the tau P301L mutation, a strong and age-dependent decrease of EAAT2 expression was demonstrated. Restoration of EAAT2 activity in the AD mice following treatment with all the ?-lactam antibiotic Cef was associated with a decrease in cognitive impairment and reduced tau pathology. In human AD brains, decreased expression of EAAT2 protein and a decrease in EAAT action was determined. However,� this outcome measure could not be replicated by other researchers. On the transcriptome level, research studies discovered exon-skipping splice variations of EAAT2 which reduce glutamate transport activity to be upregulated in human AD brains. From the CSF, several groups demonstrated an increase in glutamate concentrations in AD patients where other groups demonstrated absolutely no change or even diminished levels of L-glutamate associated with Alzheimer’s disease. �

In vitro, A? causes L-glutamate discharge from primary microglia through the upregulation of program x?c. Others discovered that it also triggered L-glutamate release from astrocytes through the activation of the ?7 nicotinic acetylcholine receptor. Additionally, xCT, the specific subunit of system x?c is upregulated at the region of senile plaques, possibly in microglial cells, in Thy1-APP751 mice (TgAPP) expressing human APP bearing the Swedish (S: KM595/596NL) and London (L: V6421) mutations after A? injection in the hippocampus. Semiquantitative immunoblot evaluations revealed an upregulation of xCT protein expression in the frontal cortex in elderly A?PP23 mice compared to wild-type controls. �

Postmortem research studies show that KYN metabolism affects AD elevated concentrations of KYNA while also discovered in the basal ganglia of both AD sufferers. Utilizing immunohistochemistry, research studies demonstrated immunoreactivity for both IDO and QUIN upregulated in AD brains, particularly in the vicinity of plaques. A? causes IDO expression in human primary macrophages and microglia. Systemic inhibition of KMO ultimately increases brain KYNA levels and ameliorated the phenotype of a mouse model of AD, indicating an upregulation of KYNA may be an endogenous protective reaction, including the IDO inhibitor, coptisine, decreased microglial, astrocytic activation and cognitive impairment in AD mice. �

Taken together, along with many other harmful changes, there is evidence for chronic excitotoxicity in AD which can be driven by numerous variables, including the central sensitization of both NMDA receptors, a decrease in L-glutamate and L-aspartate reuptake capacity and an increase in glutamate release through system x?c, as shown in Figure 4. Although the KYN pathway seems to be upregulated in AD, no specific conclusions can be drawn regarding glutamatergic neurotransmission from the upregulation of the two QUIN which was neurotoxic and neuroprotective KYNA. �

�

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

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 �

1. 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 Zoomer^TM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural Zoomer^TM 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 Zoomer^TM 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.

�

Functional Neurology: Chronic Excitotoxicity in Neurodegenerative Diseases

by Dr Alex Jimenez | Nerve Injury, Neuropathy

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 �

1. 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 Zoomer^TM Plus is an array of neurological autoantibodies which offers specific antibody-to-antigen recognition. The Vibrant Neural Zoomer^TM 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 Zoomer^TM 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.

�