Neurotransmitter Glutamate Research Articles

GABA and glutamate measurements in temporal cortex of autistic children.

Autism spectrum disorder (ASD) is a neurodevelopmental disorder and presents with challenges in social communication. A hypothesized underlying contributing mechanism is the imbalance in excitation and inhibition (E/I), partly influenced by the levels of excitatory neurotransmitter glutamate (Glu) and inhibitory neurotransmitter γ-aminobutyric acid (GABA) in the brain. Although many have reported the levels of GABA and Glu in the brain, only a few reports address the temporal cortex and then only with a small sample of autistic children, and often only in one hemisphere. We used a macromolecular suppressed edited-magnetic resonance spectroscopy (MRS) sequence to study GABA and Glu (as potential key players influencing E/I) in a large sample of children with ASD in the right and left temporal cortices of children with (N = 56) and without (N = 30) ASD (7-18 years). As a group, children with ASD exhibited no differences in the left hemisphere (GABA and Glu Cohen's |d|: 0.24 and 0.03), but the right hemisphere showed higher GABA and lower Glu concentrations (GABA and Glu Cohen's |d|: 0.53 and 0.65) compared to neurotypicals. Furthermore, a negative association was found between the right hemisphere Glu levels of the ASD group and a clinical assessment tool (r = -0.361, p = 0.022), reflecting autism trait severity (social responsiveness scale). In conclusion, we highlight the chemical abnormalities in children with ASD through a cross-sectional measurement. Longitudinal studies are warranted to determine whether these chemical levels persist or resolve over development.

EXTH-35. REPURPOSING OF CLINICALLY APPROVED GLUTAMATE ANTAGONISTS TO TREAT GLIOBLASTOMA

Abstract The neurotransmitter glutamate plays a fundamental role in promoting epilepsy and tumor progression in glioblastoma. Glioblastoma cells secrete glutamate into the tumor microenvironment via the cystine-glutamate antiporter system Xc, leading to neuronal hyperexcitability, excitotoxicity, and tumor cell invasion. Additionally, glutamatergic neuroglioma synapses drive glioma progression in preclinical tumor models. To pharmacologically counteract effects of glutamate in glioblastoma, we employed a triple combination of anti-glutamatergic drugs: gabapentin, sulfasalazine, and memantine, which target glutamate synthesis, release, and post-synaptic signaling, respectively. In genetically engineered murine glioblastoma models, daily treatment with this triple combination prolonged median survival. This survival benefit was not observed with single or double drug combinations, nor with the standard antiepileptic drug levetiracetam, indicating the potential synergy and efficacy of this drug combination beyond merely treating epilepsy. Importantly, these preliminary results support the rationale for the ongoing phase Ib/II randomized clinical trial GLUGLIO, which explores the efficacy of combined gabapentin, sulfasalazine, and memantine in conjunction with standard chemoradiotherapy in patients with newly diagnosed glioblastoma (NCT05664464).

GC-MS uncovers unique metabolic markers of drug-resistant epilepsy in capillary but not venous dried blood spots

This study compared the effectiveness of capillary dried blood spots (DBS) versus venous DBS in detecting metabolic changes related to drug-resistant epilepsy (DRE). DBS samples were collected from 142 epilepsy patients (58 drug-resistant, 84 drug-responsive) via venipuncture or fingerstick capillary sampling. Metabolomic analysis using gas chromatography-mass spectrometry compared DBS metabolite profiles between the two groups. While venous DBS profiles showed no distinct patterns, capillary DBS profiles revealed clustering patterns in principal components analysis, with the first two principal components explaining 14.5%, and 13.5% of the total variance, respectively. Orthogonal PLS-DA confirmed group discrimination (R2Y=0.989, Q2=0.742). Drug-resistant patients exhibited elevated capillary DBS levels of glutamine, pyruvic acid, and serine, and decreased palmitic acid compared to drug-responsive patients. Pathway analysis revealed disruptions in amino acid metabolism, neurotransmission, and cellular energy regulation. Elevated glutamine levels may contribute to an imbalance between excitatory glutamate and inhibitory GABA neurotransmission, key factors in epileptogenesis and drug resistance. Capillary DBS, likely enriched with arterial blood supply to the brain, appears to better capture central nervous system metabolic disturbances compared to venous DBS containing systemic contributions. This minimally invasive capillary DBS approach offers effective metabolic profiling of brain conditions like DRE, for monitoring disease progression and treatment response, enhancing personalized patient management in epilepsy.

Time-restricted feeding prevents memory impairments induced by obesogenic diet consumption, via hippocampal thyroid hormone signaling

ObjectivesThe early consumption of calorie-rich diet disrupts circadian rhythms and has adverse effects on memory, yet the effects of time-restricted feeding (TRF) and the underlying molecular mechanisms are unknown. Here, we set out to identify the behavioral and molecular circadian rhythms disruptions generated by juvenile obesogenic diet consumption and their restoration by TRF in male mice. MethodsMetabolic rhythms were measured by indirect calorimetry and memory performances by behavioral tasks. Hippocampal translatome (pS6_TRAP), enrichment and co-regulated gene network analyses were conducted to identify the molecular pathways involved in memory impairments and their restoration by TRF. Differential exon usage analyses, mass spectrometry and pharmacological intervention were used to confirm thyroid hormone signaling involvement. ResultsWe show that four weeks of TRF restore the rhythmicity of metabolic parameters and prevents memory impairments in mice fed a high fat-high sucrose (HFS) diet since weaning, independently of body fat levels. Hippocampal translatome and differential exon usage analyses indicate that impaired memory of mice under ad libitum HFS diet is accompanied by reduced thyroid hormone signaling and altered expression of astrocytic genes regulating glutamate neurotransmission. TRF restored the diurnal expression variation of part of these genes and intra-hippocampal infusion of T3, the active form of thyroid hormone, rescues memory performances and astrocytic gene expression of ad libitum HFS diet-fed mice. ConclusionsThus, thyroid hormones contribute to the TRF positive effects on both metabolism and memory in mice fed an obesogenic diet, highlighting this nutritional approach as a powerful tool in addressing obesity brain comorbidities and paving the way for further mechanistic studies on hippocampal thyroid signaling.

Is There such a Thing as Post-Viral Depression?: Implications for Precision Medicine.

Viral infections are increasingly recognized as triggers for depressive disorders, particularly following the SARS-CoV-2 pandemic and the rise of long COVID. Viruses such as Herpes Simplex Virus (HSV), Epstein-Barr Virus (EBV), Cytomegalovirus (CMV), and Human Immunodeficiency Virus (HIV) are linked to depression through complex neurobiological mechanisms. These include immune system dysregulation, chronic inflammation, and neurotransmitter imbalances that affect brain function and mood regulation. Viral activation of the immune system leads to the release of pro-inflammatory cytokines, resulting in neuroinflammation and associated depressive symptoms. Furthermore, specific viruses can disrupt neurotransmitter systems, including serotonin, dopamine, and glutamate, all of which are essential for mood stabilization. The unique interactions of different viruses with these systems underscore the need for virus-specific therapeutic approaches. Current broad-spectrum treatments often overlook the precise neurobiological pathways involved in post-viral depression, reducing their efficacy. This review emphasizes the need to understand these virus-specific interactions to create tailored interventions that directly address the neurobiological effects induced by each type of virus. These interventions may include immunomodulatory treatments that target persistent inflammation, antiviral therapies to reduce the viral load, or neuroprotective strategies that restore neurotransmitter balance. Precision medicine offers promising avenues for the effective management of virus-induced depression, providing patient-specific approaches that address the specific biological mechanisms involved. By focusing on the development of these targeted treatments, this review aims to pave the way for a new era in psychiatric care that fully addresses the root causes of depression induced by viral infections.

Activation of ionotropic and group I metabotropic glutamate receptors stimulates kisspeptin neuron activity in mice.

Different populations of hypothalamic kisspeptin (KISS1) neurons located in the rostral periventricular area of the third ventricle (RP3V) and arcuate nucleus (ARC) are thought to generate the sex-specific patterns of gonadotropin secretion. These neuronal populations integrate gonadal sex steroid feedback with internal and external cues relayed via the actions of neurotransmitters and neuropeptides. The excitatory amino acid neurotransmitter glutamate, the main excitatory neurotransmitter in the brain, plays a role in regulating gonadotropin secretion, at least partially through engaging KISS1 signaling. The expression and function of individual glutamate receptor subtypes in KISS1 neurons, however, are not well characterized. Here, we used GCaMP-based calcium imaging and patch-clamp electrophysiology to assess the impact of activating individual ionotropic (iGluR) and group I metabotropic (mGluR) glutamate receptors on KISS1 neuron activity in the mouse RP3V and ARC. Our results indicate that activation of all iGluR subtypes and of group I mGluRs, likely mGluR1, consistently drives activity in the majority of KISS1 neurons within the RP3V and ARC of males and females. Our results also revealed, somewhat unexpectedly, sex- and region-specific differences. Indeed, activating (S)-α-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) type iGluRs evoked larger responses in female ARCKISS1 neurons than in their male counterparts whereas activating group I mGluRs induced larger responses in RP3VKISS1 neurons than in ARCKISS1 neurons in females. Together, our findings suggest that glutamatergic neurotransmission in KISS1 neurons, and its impact on the activity of these cells, might be sex- and region-dependent in mice.

Typical Pathological Process in Glutamate Neurotoxicity: the Role of Reactive Nitrogen and Oxygen Species

The disruption of major regulatory mechanisms of nerve cells can lead to glutamate neurotoxicity/excitotoxicity. This phenomenon most often occurs in hypoxia/ischemia, during inflammatory processes, activation of immune and autoimmune responses. Pathological changes in the brain in the early stages of diseases are nonspecific. The distinction between pathological change and physiological norm is small. These typical pathological processes are common with a variety of diseases. They may also occur in ischemic and hemorrhagic strokes. The main objective of this work was to analyze some physiological and cytochemical processes that are associated with the neurotransmitter glutamate, as well as with highly reactive and highly toxic compounds such as reactive nitrogen and oxygen species. Reactive nitrogen (•NO) and oxygen (•O2–) species can affect almost all major components of cells and subcellular structures. At low concentrations, they perform a regulatory function. Mechanism analysis of toxic effects of glutamate, reactive nitrogen and oxygen species was essential for the development of new methods of protection against the damaging effects of the said substances thereby using these methods in treatment of ischemic and hemorrhagic strokes.

Exploring the role of AMPA receptor auxiliary proteins in synaptic functions and diseases.

α-Amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA) ionotropic glutamate receptors (AMPARs) mediate rapid excitatory synaptic transmission in the mammalian brain, primarily driven by the neurotransmitter glutamate. The modulation of AMPAR activity, particularly calcium-permeable AMPARs (CP-AMPARs), is crucially influenced by various auxiliary subunits. These subunits are integral membrane proteins that bind to the receptor's core and modify its functional properties, including ion channel kinetics and receptor trafficking. This review comprehensively catalogs all known AMPAR auxiliary proteins, providing vital insights into the biochemical mechanisms governing synaptic modulation and the specific impact of CP-AMPARs compared to their calcium-impermeable AMPA receptor (CI-AMPARs). Understanding the complex interplay between AMPARs and their auxiliary subunits in different brain regions is essential for elucidating their roles in cognitive functions such as learning and memory. Importantly, alterations in these auxiliary proteins' expression, function or interactions have been implicated in various neurological disorders. Aberrant signaling through CP-AMPARs, in particular, is associated with severe synaptic dysfunctions across neurodevelopmental, neurodegenerative and psychiatric conditions. Targeting the distinct properties of AMPAR-auxiliary subunit complexes, especially those involving CP-AMPARs, could disclose new therapeutic strategies, potentially allowing for more precise interventions in treating complex neuronal disorders.

8372 Evidence of dACC Glutamate Modulation During Top-down Inhibitory Control Predicting Weight Loss Ability in Individuals with Obesity Using1H fMRS

Abstract Disclosure: J.M. Eichstaedt: None. R. Sochocki: None. D. Khatib: None. N. Miller: None. V.A. Diwadkar: None. P. Burghardt: None. A.E. Rothberg: None. J.A. Stanley: None. Poor weight loss maintenance (WLM) following dietary intervention has been associated with poor top-down inhibitory control. The neurobiological mechanisms are not fully understood; it is not clear if changes to inhibitory control are specific to the presence of appetitive food cues. The dorsal anterior cingulate cortex (dACC) is central to inhibitory control and can be conceptualized selectively withholding ‘prepotent’ motor responses. This is driven by highly integrated glutamatergic and GABAergic neurotransmission. Temporal changes in glutamate, reflecting shifts in glutamate neurotransmission, can be detected under distinct processes or task conditions using [1]H fMRS. We investigated differences in dACC glutamate under task conditions with or without inhibitory motor control, utilizing neutral Squares and Food/Non-food stimuli, and their association with weight loss. Data were acquired from 13 individuals with obesity following dietary intervention resulting in 10% weight loss (5F; mean age: 50.1±5.2yrs). A visually-guided motor tapping task was used requiring participants to respond to stimuli under two modes, “Non-Selective” (motor responses to 100% of trials) and “Selective” (withholding responses on 20% of trials - involving both motor control and inhibition), and under two stimuli types (Squares and appetitive Food/Non-Food cues). Glutamate modulation changes (relative to the total signal) were assessed across stimuli type (independent of task mode) using repeated measures generalizing estimating equations (GEE) approach (SAS GENMOD). The correlation between glutamate during the Selective mode with food/non-food stimuli and percentage of weight lost during the dietary intervention was also assessed. The stimuli model term was not significant (χ2=3.50, p=0.174), but post hoc analysis indicated significantly increased glutamate during the Squares (z=-1.99, p=0.046), but not the Food/Non-food (z=-1.39, p=0.163) relative to baseline. A trending correlation between decreasing dACC glutamate modulation (Selective mode, Food/Non-Food) and decreasing percentage of weight lost during the intervention was observed (R2=0.274, F(1,11)=4.15, p=0.07). This suggests that the presence of appetitive food cues leads to a non-significant change in the dACC glutamate modulation independent of inhibitory or motor alone responses. The potential correlation between dACC glutamate modulation and weight loss provides preliminary support that appetitive food cues influence inhibitory control and the extent of the influences may be related to one’s ability to maintain weight loss. These results could provide greater understanding of the neurobiological mechanisms underlying top-down inhibitory processes influenced by affect and difficulties with weight loss and maintenance, potentially fueling better treatment for successful long-term WLM in obesity. Presentation: 6/1/2024

Protective role of ghrelin against 6PPD-quinone-induced neurotoxicity in zebrafish larvae (Danio rerio) via the GHSR pathway

The toxicity mechanisms of N-(1,3-dimethylbutyl)-N′-phenyl-p-phenylenediamine quinone (6PPD-Q), an antioxidant derivative of 6PPD via ozone reaction commonly used in rubber and tire industries, were investigated in zebrafish larvae with concentrations ranging from 0 to 50 μg/L. Despite normal hatchability, 6PPD-Q exposure led to reduced body length and swimming distance in 120 hours post-fertilization (hpf) larvae. At the highest concentration (50 μg/L), 6PPD-Q significantly impaired dopaminergic neuron development and neurotransmitter levels, including dopamine, 5-hydroxytryptamine, and glutamate. Transcriptome profiling unveiled perturbations in growth and developmental gene expression, such as upregulation of runx2a, runx2b, and ghrl (ghrelin and obestatin prepropeptide), and downregulation of stat1b, auto1, and cidea. Notably, anamorelin, a growth hormone secretagogue receptor (GHSR) agonist, recovered the behavioral deficits induced by 6PPD-Q, implying a neuroprotective role of ghrelin possibly mediated via the ghrelin/GHSR pathway. Collectively, our findings indicate that ghrelin upregulation may counteract 6PPD-Q toxicity in zebrafish larvae, shedding light on potential therapeutic avenues for mitigating the adverse effects of this antioxidant byproduct.

Metal-Organic Framework Nanofluidic Synapse.

Chemical synapse completes the signaling through neurotransmitter-mediated ion flux, the emulation of which has been a long-standing obstacle in neuromorphic exploration. Here, we report metal-organic framework (MOF) nanofluidic synapses in which conjugated MOFs with abundant ionic storage sites underlie the ionic hysteresis and simultaneously serve as catalase mimetics that sensitively respond to neurotransmitter glutamate (Glu). Various neurosynaptic patterns with adaptable weights are realized via Glu-mediated chemical/ionic coupling. In particular, nonlinear Hebbian and anti-Hebbian learning in millisecond time ranges are achieved, akin to those of chemical synapses. Reversible biochemical in-memory encoding via enzymatic Glu clearance is also accomplished. Such results are prerequisites for highly bionic electrolytic computers.

Genomic study of taste perception genes in African Americans reveals SNPs linked to Alzheimer’s disease

While previous research has shown the potential links between taste perception pathways and brain-related conditions, the area involving Alzheimer’s disease remains incompletely understood. Taste perception involves neurotransmitter signaling, including serotonin, glutamate, and dopamine. Disruptions in these pathways are implicated in neurodegenerative diseases. The integration of olfactory and taste signals in flavor perception may impact brain health, evident in olfactory dysfunction as an early symptom in neurodegenerative conditions. Shared immune response and inflammatory pathways may contribute to the association between altered taste perception and conditions like neurodegeneration, present in Alzheimer’s disease. This study consists of an exploration of expression-quantitative trait loci (eQTL), utilizing whole-blood transcriptome profiles, of 28 taste perception genes, from a combined cohort of 475 African American subjects. This comprehensive dataset was subsequently intersected with single-nucleotide polymorphisms (SNPs) identified in Genome-Wide Association Studies (GWAS) of Alzheimer’s Disease (AD). Finally, the investigation delved into assessing the association between eQTLs reported in GWAS of AD and the profiles of 741 proteins from the Olink Neurological Panel. The eQTL analysis unveiled 3,547 statistically significant SNP-Gene associations, involving 412 distinct SNPs that spanned all 28 taste genes. In 17 GWAS studies encompassing various traits, a total of 14 SNPs associated with 12 genes were identified, with three SNPs consistently linked to Alzheimer’s disease across four GWAS studies. All three SNPs demonstrated significant associations with the down-regulation of TAS2R41, and two of them were additionally associated with the down-regulation of TAS2R60. In the subsequent pQTL analysis, two of the SNPs linked to TAS2R41 and TAS2R60 genes (rs117771145 and rs10228407) were correlated with the upregulation of two proteins, namely EPHB6 and ADGRB3. Our investigation introduces a new perspective to the understanding of Alzheimer's disease, emphasizing the significance of bitter taste receptor genes in its pathogenesis. These discoveries set the stage for subsequent research to delve into these receptors as promising avenues for both intervention and diagnosis. Nevertheless, the translation of these genetic insights into clinical practice requires a more profound understanding of the implicated pathways and their pertinence to the disease's progression across diverse populations.

Glucocorticoid receptor signaling in the brain and its involvement in cognitive function.

The hypothalamic-pituitary-adrenal axis regulates the secretion of glucocorticoids in response to environmental challenges. In the brain, a nuclear receptor transcription factor, the glucocorticoid receptor, is an important component of the hypothalamic-pituitary-adrenal axis's negative feedback loop and plays a key role in regulating cognitive equilibrium and neuroplasticity. The glucocorticoid receptor influences cognitive processes, including glutamate neurotransmission, calcium signaling, and the activation of brain-derived neurotrophic factor-mediated pathways, through a combination of genomic and non-genomic mechanisms. Protein interactions within the central nervous system can alter the expression and activity of the glucocorticoid receptor, thereby affecting the hypothalamic-pituitary-adrenal axis and stress-related cognitive functions. An appropriate level of glucocorticoid receptor expression can improve cognitive function, while excessive glucocorticoid receptors or long-term exposure to glucocorticoids may lead to cognitive impairment. Patients with cognitive impairment-associated diseases, such as Alzheimer's disease, aging, depression, Parkinson's disease, Huntington's disease, stroke, and addiction, often present with dysregulation of the hypothalamic-pituitary-adrenal axis and glucocorticoid receptor expression. This review provides a comprehensive overview of the functions of the glucocorticoid receptor in the hypothalamic-pituitary-adrenal axis and cognitive activities. It emphasizes that appropriate glucocorticoid receptor signaling facilitates learning and memory, while its dysregulation can lead to cognitive impairment. This provides clues about how glucocorticoid receptor signaling can be targeted to overcome cognitive disability-related disorders.

Estradiol elicits distinct firing patterns in arcuate nucleus kisspeptin neurons of females through altering ion channel conductances.

Hypothalamic kisspeptin (Kiss1) neurons are vital for pubertal development and reproduction. Arcuate nucleus Kiss1 (Kiss1ARH) neurons are responsible for the pulsatile release of Gonadotropin-releasing Hormone (GnRH). In females, the behavior of Kiss1ARH neurons, expressing Kiss1, Neurokinin B (NKB), and Dynorphin (Dyn), varies throughout the ovarian cycle. Studies indicate that 17β-estradiol (E2) reduces peptide expression but increases Vglut2 mRNA and glutamate neurotransmission in these neurons, suggesting a shift from peptidergic to glutamatergic signaling. To investigate this shift, we combined transcriptomics, electrophysiology, and mathematical modeling. Our results demonstrate that E2 treatment upregulates the mRNA expression of voltage-activated calcium channels, elevating the whole-cell calcium current and that contribute to high-frequency burst firing. Additionally, E2 treatment decreased the mRNA levels of Canonical Transient Receptor Potential (TPRC) 5 and G protein-coupled K+ (GIRK) channels. When TRPC5 channels in Kiss1ARH neurons were deleted using CRISPR, the slow excitatory postsynaptic potential (sEPSP) was eliminated. Our data enabled us to formulate a biophysically realistic mathematical model of the Kiss1ARH neuron, suggesting that E2 modifies ionic conductances in Kiss1ARH neurons, enabling the transition from high frequency synchronous firing through NKB-driven activation of TRPC5 channels to a short bursting mode facilitating glutamate release. In a low E2 milieu, synchronous firing of Kiss1ARH neurons drives pulsatile release of GnRH, while the transition to burst firing with high, preovulatory levels of E2 would facilitate the GnRH surge through its glutamatergic synaptic connection to preoptic Kiss1 neurons.

N-Methyl-D-Aspartate (NMDA) Receptor Antagonists and their Pharmacological Implication: A Medicinal Chemistry-oriented Perspective Outline.

N-methyl-D-aspartate (NMDA) receptors, i.e., inotropic glutamate receptors, are important in synaptic plasticity, brain growth, memory, and learning. The activation of NMDA is done by neurotransmitter glutamate and co-agonist (glycine or D-serine) binding. However, the over-activation of NMDA elevates the intracellular calcium influx, which causes various neurological diseases and disorders. Therefore, to prevent excitotoxicity and neuronal death, inhibition of NMDA must be done using its antagonist. This review delineates the structure of subunits of NMDA and the conformational changes induced after the binding of agonists (glycine and D-serine) and antagonists (ifenprodil, etc.). Additionally, reported NMDA antagonists from different sources, such as synthetic, semisynthetic, and natural resources, are explained by their mechanism of action and pharmacological role. The comprehensive report also addresses the chemical spacing of NMDA inhibitors and in-vivo and in-vitro models to test NMDA antagonists. Since the Blood-Brain Barrier (BBB) is the primary membrane that prevents the penetration of a wide variety of drug molecules, we also elaborate on the medicinal chemistry approach to improve the effectiveness of their antagonists.

Abstract P385: Effects Of a High Salt Diet On Glutamatergic Signaling In The Nucleus Of The Solitary Tract And Baroreflex Sensitivity

Hypertension remains a global health concern. Studies have shown a correlation with the loss of normal 24-hour blood pressure patterns and hypertension with a high salt diet. However, the mechanisms behind this are not fully known. The nucleus of the solitary tract (nTS), a key medullary nucleus involved in cardiorespiratory regulation, is known to modulate sympathetic outflow and blood pressure alterations.When blood pressure increases, baroreceptors in peripheral vessels detect these changes and send signals to the nTS through the neurotransmitter glutamate. Increased nTS glutamatergic signaling decreases blood pressure via efferent signals to the heart and blood vessels. The nTS integrates these signals and initiates responses through the baroreflex to counteract changes in blood pressure. Thus, baroreflex sensitivity (BRS), or a measure of how the baroreflex adjusts, serves as an indicator of the regulation of this feedback loop. An increased BRS indicates a more robust ability of the body to respond to blood pressure changes. Conversely, a reduced BRS is associated with hypertension, and autonomic dysfunction. Studies have shown that those with diet-induced hypertension also have a decreased BRS, however, the mechanism is not clear. We hypothesize that dysregulation of the 24-hour circadian glutamatergic signaling within the nTS may cause BRS decrease and hypertension. Salt-sensitive rats were subjected to either a normal salt diet (NSD, 0.4 % NaCl) or high salt diet (HSD, 4% NaCl) for 7 weeks. To determine nTS changes related to HSD, we measured blood pressure using 24/7 telemetry, and activation of glutamatergic neurons via immunohistochemistry (IHC). Antibodies against glutamate (CAMKII) and neuronal activation (cFos) were used to detect neuronal activation 6 hours apart, at the end of the NSD or HSD. Our preliminary findings reveal near significant decreases in glutamate signaling during the active period (at 9pm), suggesting a potential shift in the excitatory signaling in the nTS. Additionally, HSD over 7 weeks caused a significant increase in blood pressure and a decrease in BRS during the active period. Our preliminary data shows a connection between 24-hour regulation of glutamate within the nTS, diet-induced hypertension, and loss of BRS. This dysregulation in the blood pressure regulation underscores the importance of understanding the molecular mechanisms linking diet and development of disease.

RTMS mechanisms for posttraumatic stress disorder treatment in a mouse model

BackgroundPosttraumatic stress disorder (PTSD) is a psychiatric disease that may follow traumatic exposure. Current treatments fail in about 30% of patients. Although repeated transcranial magnetic stimulation (rTMS) applied to the prefrontal cortex has been shown to be effective in the treatment of PTSD, the mechanisms need further investigation. ObjectiveUsing a PTSD animal model, we verify the beneficial effect of rTMS, and explore the changes it induces on two putative PTSD mechanisms, GABA/glutamate neurotransmission and neuroinflammation. MethodsPTSD-like symptoms were elicited in twenty-six mice using a foot-shock conditioning procedure. Fourteen of the 26 were then treated using rTMS (12 were untreated). In the control group (n = 30), 18 were treated with rTMS and 12 were untreated. Animals were sacrificed after re-exposure. The infralimbic (IL) cortex, basolateral amygdala (BLA) and ventral CA1 (vCA1) were isolated using laser microdissection. mRNA was then investigated using PCR array analysis targeting GABA/glutamate and inflammatory pathways. ResultsThe rTMS treatment significantly decreased the contextual fear memory phenotype. These changes were associated with reduced mRNA expression related to inflammation in the IL cortex and the vCA1, and lowered mRNA-related glutamate neurotransmission and increased GABA neurotransmission in the BLA. ConclusionOur results suggest that our rTMS treatment was associated with local anti-inflammatory effects and limbic effects, which seemed to counteract PTSD effects. Several of these changes (both stress- and rTMS-induced) have implications for the drug sensitivity of limbic brain areas, and may help in the design of future therapeutic protocols.

Lamotrigine: A Safe and Effective Mood Stabilizer for Bipolar Disorder in Reproductive-Age Adults.

Lamotrigine belongs to the group of antiepileptic drugs and mood stabilizers, and its action is based on the selective blocking of voltage-deficient sodium channels. The effect of this mechanism is the stabilization of the presynaptic part of the neuronal membrane and subsequent inhibition of the secretion of the neurotransmitters glutamate and aspartate into the postsynaptic part of the neuron. Lamotrigine has been approved by the Food and Drug Administration for the maintenance treatment of adults with bipolar disorder since 1994. In the field of psychiatry, this medicine is also used off-label in the treatment of acute bipolar depression. Studies show promising effects of the use of lamotrigine in bipolar disorder type II with rapid phase change. Bipolar disorder is a common psychiatric problem that most often affects young adults. Lamotrigine is most effective in bipolar disorder in preventing depressive episodes, which dominate the clinical picture of this disease. The latest research focuses on extending its action, to include manic episodes. Lamotrigine, through an unexplained mechanism, can affect the immune system, causing Stevens-Johnson syndrome, hemophagocytic lymphohistiocytosis, and drug reaction with eosinophilia and systemic symptoms syndrome. These are rare, life-threatening adverse effects that require urgent intervention in the form of drug discontinuation and immunosuppressive treatment. Strict contraindications to the use of lamotrigine include sensitivity reactions accompanied by systemic symptoms. Phenotype testing enables screening of patients predisposed to serious hypersensitivity reactions. The aim of the article is to review the indications, contraindications, and adverse effects of lamotrigine in the treatment of bipolar disorder and depression.

Prefrontal Excitation/ Inhibition Balance Supports Adolescent Enhancements in Circuit Signal to Noise Ratio.

The development and refinement of neuronal circuitry allow for stabilized and efficient neural recruitment, supporting adult-like behavioral performance. During adolescence, the maturation of PFC is proposed to be a critical period (CP) for executive function, driven by a break in balance between glutamatergic excitation and GABAergic inhibition (E/I) neurotransmission. During CPs, cortical circuitry fine-tunes to improve information processing and reliable responses to stimuli, shifting from spontaneous to evoked activity, enhancing the SNR, and promoting neural synchronization. Harnessing 7T MR spectroscopy and EEG in a longitudinal cohort (N = 164, ages 10-32 years, 283 neuroimaging sessions), we outline associations between age-related changes in glutamate and GABA neurotransmitters and EEG measures of cortical SNR. We find developmental decreases in spontaneous activity and increases in cortical SNR during our auditory steady state task using 40 Hz stimuli. Decreases in spontaneous activity were associated with glutamate levels in DLPFC, while increases in cortical SNR were associated with more balanced Glu and GABA levels. These changes were associated with improvements in working memory performance. This study provides evidence of CP plasticity in the human PFC during adolescence, leading to stabilized circuitry that allows for the optimal recruitment and integration of multisensory input, resulting in improved executive function.

Inhibition of Glycyrrhiza Polysaccharide on Human Cytochrome P450 46A1 in vitro and in vivo: Implications in Treating Neurological Diseases.

Cytochrome P450 (CYP) 46A1, also known as cholesterol 24S-hydroxylase, is essential for maintaining the homeostasis of cholesterol in the brain and serves as a therapeutic target of neurodegenerative disorders and excitatory neurotoxicity. N-methyl-d-aspartate receptor (NMDAR) is a prototypical receptor for the excitatory neurotransmitter glutamate and can be specifically regulated by 24S-hydroxycholesterol (24S-HC). Glycyrrhiza is one of the most widely used herbs with broad clinical applications, which has several pharmacological activities, such as clearing heat and detoxifying, moistening the lung and relieving cough, analgesic, neuroprotective outcomes, and regulating a variety of drug activities. Glycyrrhiza is a commonly used herb for the treatment of epileptic encephalopathy. However, whether glycyrrhiza can interfere with the activity of CYP46A1 remains unknown. This study aimed to investigate the regulating effects of glycyrrhiza polysaccharides (GP) on CYP46A1-mediated cholesterol conversion, as well as in the modulation of related proteins. The effects of glycyrrhiza polysaccharide (GP) on the activity of CYP46A1 were investigated in vivo and in vitro. Moreover, the potential regulatory effects of GP on the expressions of CYP46A1, HMG-CoA reductase (HMGCR), and NMDAR were also detected. The in vitro results demonstrated that glycyrrhiza polysaccharide (GP), as the main water-soluble active component of glycyrrhiza, remarkably inhibited the activity of CYP46A1 in a non-competitive mode with a Ki value of 0.7003 mg/ml. Furthermore, the in vivo experiments verified that GP markedly decreased the contents of 24S-HC in rat plasma and brain tissues as compared to the control. More importantly, the protein expressions of CYP46A1, GluN2A, GluN2B, and HMG-CoA reductase (HMGCR) in rat brains were all downregulated, whereas the mRNA expressions of CYP46A1 and HMGCR were not significantly changed after treatment with GP. GP exhibits a significant inhibitory effect on CYP46A1 activity in vitro and in vivo, and the protein expressions of CYP46A1, HMGCR, and NMDAR are also inhibited by GP, which are of considerable clinical significance for GP's potential therapeutic role in treating neurological diseases.