Influence of glutamate and GABA transport on brain excitatory/inhibitory balance

An integrated approach to identifying sex-specific genes, transcription factors, and pathways relevant to Alzheimer's disease

BACKGROUND

Age represents a significant risk factor for the development of Alzheimer's disease (AD); however, recent research has documented an influencing role of sex in several features of AD. Understanding the impact of sex on specific molecular mechanisms associated with AD remains a critical challenge to creating tailored therapeutic interventions.

METHODS

The exploration of the sex-based differential impact on disease (SDID) in AD used a systematic review to first select transcriptomic studies of AD with data regarding sex in the period covering 2002 to 2021 with a focus on the primary brain regions affected by AD - the cortex (CT) and the hippocampus (HP). A differential expression analysis for each study and two tissue-specific meta-analyses were then performed. Focusing on the CT due to the presence of significant SDID-related alterations, a comprehensive functional characterization was conducted: protein-protein network interaction and over-representation analyses to explore biological processes and pathways and a VIPER analysis to estimate transcription factor activity.

RESULTS

We selected 8 CT and 5 HP studies from the Gene Expression Omnibus (GEO) repository for tissue-specific meta-analyses. We detected 389 significantly altered genes in the SDID comparison in the CT. Generally, female AD patients displayed more affected genes than males; we grouped said genes into six subsets according to their expression profile in female and male AD patients. Only subset I (repressed genes in female AD patients) displayed significant results during functional profiling. Female AD patients demonstrated more significant impairments in biological processes related to the regulation and organization of synapsis and pathways linked to neurotransmitters (glutamate and GABA) and protein folding, Aβ aggregation, and accumulation compared to male AD patients. These findings could partly explain why we observe more pronounced cognitive decline in female AD patients. Finally, we detected 23 transcription factors with different activation patterns according to sex, with some associated with AD for the first time. All results generated during this study are readily available through an open web resource Metafun-AD (https://bioinfo.cipf.es/metafun-ad/).

CONCLUSION

Our meta-analyses indicate the existence of differences in AD-related mechanisms in female and male patients. These sex-based differences will represent the basis for new hypotheses and could significantly impact precision medicine and improve diagnosis and clinical outcomes in AD patients.

Regional structural-functional connectivity coupling in major depressive disorder is associated with neurotransmitter and genetic profiles

BACKGROUND

Abnormalities in structural-functional connectivity (SC-FC) coupling have been identified globally in patients with major depressive disorder (MDD). However, investigations have neglected the variability and hierarchical distribution of these abnormalities across different brain regions. Furthermore, the biological mechanisms underlying regional SC-FC coupling patterns are not well understood.

METHODS

We enrolled 182 patients with MDD and 157 healthy control (HC) subjects, quantifying the intergroup differences in regional SC-FC coupling. The extreme gradient boosting (XGBoost), support vector machines (SVM) and random forest (RF) models were constructed to assess the potential of SC-FC coupling as biomarkers for MDD diagnosis and symptom prediction. Then, we examined the link between changes in regional SC-FC coupling in patients with MDD, neurotransmitter distributions, and gene expression.

RESULTS

We observed increased regional SC-FC coupling in default mode network (T = 3.233) and decreased coupling in frontoparietal network (T = -3.471) in MDD relative to HC. XGBoost (AUC = 0.853), SVM (AUC = 0.832) and RF (p < 0.05) models exhibited good prediction performance. The alterations in regional SC-FC coupling in patients with MDD were correlated with the distributions of four neurotransmitters (p < 0.05) and expression maps of specific genes. These genes were strongly enriched in genes implicated in excitatory neurons, inhibitory neurons, cellular metabolism, synapse function, and immune signaling. These findings were replicated on two brain atlases.

CONCLUSIONS

This work enhances our understanding of MDD and pave the way for the development of additional targeted therapeutic interventions.

Impact of aging on the GABAB receptor-mediated connectome

GABA B receptors (GABABRs) are heterodimeric seven-transmembrane receptors that interact with a range of proteins and form large protein complexes on cholesterol-rich membrane microdomains. As the brain ages, membrane cholesterol levels exhibit alterations, although it remains unclear how these changes impact protein-protein interactions and downstream signaling. Herein, we studied the structural bases for the interaction between GABABR and the KCC2 transporter, including their protein expression and distribution, and we compared data between young and aged rat cerebella. Also, we analyzed lipid profiles for both groups, and we used molecular dynamics simulations on three plasma membrane systems with different cholesterol concentrations, to further explore the GABABR-transporter interaction. Based on our results, we report that a significant decrease in GABAB2 subunit expression occurs in the aged rat cerebella. After performing a comparative co-immunoprecipitation analysis, we confirm that GABABR and KCC2 form a protein complex in adult and aged rat cerebella, although their interaction levels are reduced substantially as the cerebellum ages. On the other hand, our lipid analyses reveal a significant increase in cholesterol and sphingomyelin levels of the aged cerebella. Finally, we used the Martini coarse-grained model to conduct molecular dynamics simulations, from which we observed that membrane cholesterol concentrations can dictate whether the GABABR tail domains physically establish G protein-independent contacts with a transporter, and the timing when those associations eventually occur. Taken together, our findings illustrate how age-related alterations in membrane cholesterol levels affect protein-protein interactions, and how they could play a crucial role in regulating GABABR's interactome-mediated signaling.

Significance Statement

This study elucidates age-related changes in cerebellar GABAB receptors (GABABRs), KCC2, and plasma membrane lipids, shedding light on mechanisms underlying neurological decline. Molecular dynamics simulations reveal how membrane lipids influence protein-protein interactions, offering insights into age-related neurodegeneration. The findings underscore the broader impact of cerebellar aging on motor functions, cognition, and emotional processing in the elderly. By elucidating plasma membrane regulation and GABAergic dynamics, this research lays the groundwork for understanding aging-related neurological disorders and inspires further investigation into therapeutic interventions.

Huanglian Jiedu decoction alleviates ischemia-induced cerebral injury in rats by mitigating NET formation and activiting GABAergic synapses

Huanglian Jiedu decoction (HLJD) has been used to treat ischemic stroke in clinic. However, the detailed protective mechanisms of HLJD on ischemic stroke have yet to be elucidated. The aim of this study is to elucidate the underlying pharmacological mechanisms of HLJD based on the inhibition of neuroinflammation and the amelioration of nerve cell damage. A middle cerebral artery occlusion reperfusion (MCAO/R) model was established in rats and received HLJD treatment. Effects of HLJD on neurological function was assessed based on Bederson's score, postural reflex test and asymmetry score. 2, 3, 5-Triphenyltetrazolium chloride (TTC) staining, Hematein and eosin (HE) and Nissl staining were used to observe the pathological changes in brain. Then, transcriptomics was used to screen the differential genes in brain tissue in MCAO/R model rats following HLJD intervention. Subsequently, the effects of HLJD on neutrophil extracellular trap (NET) formation-related neuroinflammation, gamma-aminobutyric acid (GABA)ergic synapse activation, nerve cell damage and proliferation were validated using immunofluorescence, western blot and enzyme-linked immunosorbent assay (ELISA). Our results showed that HLJD intervention reduced the Bederson's score, postural reflex test score and asymmetry score in MCAO/R model rats. Pathological staining indicated that HLJD treatment decreased the cerebral infarction area, mitigated neuronal damage and increased the numbers of Nissl bodies. Transcriptomics suggested that HLJD affected 435 genes in MCAO/R rats. Among them, several genes involving in NET formation and GABAergic synapses pathways were dysregulated. Subsequent experimental validation showed that HLJD reduced the MPO+CitH3+ positive expression area, reduced the protein expression of PAD4, p-P38/P38, p-ERK/ERK and decreased the levels of IL-1β, IL-6 and TNF-α, reversed the increase of Iba1+TLR4+, Iba1+p65+ and Iba1+NLRP3+ positive expression area in brain. Moreover, HLJD increased GABA levels, elevated the protein expression of GABRG1 and GAT3, decreased the TUNEL positive expression area and increased the Ki67 positive expression area in brain. HLJD intervention exerts a multifaceted positive impact on ischemia-induced cerebral injury in MCAO/R rats. This intervention effectively inhibits neuroinflammation by mitigating NET formation, and concurrently improves nerve cell damage and fosters nerve cell proliferation through activating GABAergic synapses.

Choline chloride shows gender-dependent positive effects on social deficits, learning/memory impairments, neuronal loss and neuroinflammation in the lipopolysaccharide-induced rat model of autism

The neuroprotective effects of choline chloride, an essential nutrient, a precursor for the acetylcholine and synthesis of membrane phospholipids, have been associated with neurological and neurodegenerative diseases. Its contribution to autism spectrum disorder, a neurodevelopmental disorder, remains unknown. Thus, we aimed to evaluate the effects of choline chloride on social behaviours, and histopathological and biochemical changes in a rat autism model. The autism model was induced by administration of 100 μg/kg lipopolysaccharide (LPS) on the 10th day of gestation. Choline chloride treatment (100 mg/kg/day) was commenced on PN5 and maintained until PN50. Social deficits were assessed by three-chamber sociability, open field, and passive avoidance learning tests. Tumour necrosis factor alpha (TNF-α), interleukin-2 (IL) and IL-17, nerve growth factor (NGF), and glutamate decarboxylase 67 (GAD67) levels were measured to assess neuroinflammatory responses. In addition, the number of hippocampal and cerebellar neurons and glial fibrillary acidic protein (GFAP) expression were evaluated. Social novelty and passive avoidance learning tests revealed significant differences in choline chloride-treated male rats compared with saline-treated groups. TNF-α, IL-2, and IL-17 were significantly decreased after choline chloride treatment in both males and females. NGF and GAD67 levels were unchanged in females, while there were significant differences in males. Histologically, significant changes in terms of gliosis were detected in hippocampal CA1 and CA3 regions and cerebellum in choline chloride-treated groups. The presence of ameliorative effects of choline chloride treatment on social behaviour and neuroinflammation through neuroinflammatory, neurotrophic, and neurotransmission pathways in a sex-dependent rat model of LPS-induced autism was demonstrated.

Unveiling the shield: Troglitazone's impact on epilepsy-induced nerve injury through ferroptosis inhibition

BACKGROUND

Epilepsy is a widespread central nervous system disorder with an estimated 50 million people affected globally. It is characterized by a bimodal incidence peak among infants and the elderly and is influenced by a variety of risk factors, including a significant genetic component. Despite the use of anti-epileptic drugs (AEDs), drug-refractory epilepsy develops in about one-third of patients, highlighting the need for alternative therapeutic approaches.

AIMS

The primary aim of this study was to evaluate the neuroprotective effects of troglitazone (TGZ) in epilepsy and to explore the potential mechanisms underlying its action.

METHODS

We employed both in vitro and in vivo models to assess TGZ's effects. The in vitro model involved glutamate-induced toxicity in HT22 mouse hippocampal neurons, while the in vivo model used kainic acid (KA) to induce epilepsy in mice. A range of methods, including Hoechst/PI staining, CCK-8 assay, flow cytometry, RT-PCR analysis, Nissl staining, scanning electron microscopy, and RNA sequencing, were utilized to assess various parameters such as cellular damage, viability, lipid-ROS levels, mitochondrial membrane potential, mRNA expression, seizure grade, and mitochondrial morphology.

RESULTS

Our results indicate that TGZ, at doses of 5 or 20 mg/kg/day, significantly reduces KA-induced seizures and neuronal damage in mice by inhibiting the process of ferroptosis. Furthermore, TGZ was found to prevent changes in mitochondrial morphology. In the glutamate-induced HT22 cell damage model, 2.5 μM TGZ effectively suppressed neuronal ferroptosis, as shown by a reduction in lipid-ROS accumulation, a decrease in mitochondrial membrane potential, and an increase in PTGS2 expression. The anti-ferroptotic effect of TGZ was confirmed in an erastin-induced HT22 cell damage model as well. Additionally, TGZ reversed the upregulation of Plaur expression in HT22 cells treated with glutamate or erastin. The downregulation of Plaur expression was found to alleviate seizures and reduce neuronal damage in the mouse hippocampus.

CONCLUSION

This study demonstrates that troglitazone has significant therapeutic potential in the treatment of epilepsy by reducing epileptic seizures and the associated brain damage through the inhibition of neuronal ferroptosis. The downregulation of Plaur expression plays a crucial role in TGZ's anti-ferroptotic effect, offering a promising avenue for the development of new epilepsy treatments.

Sodium p-perfluorinated noneoxybenzen sulfonate (OBS) induced neurotoxicity in zebrafish through mitochondrial dysfunction

Sodium p-perfluorous nonenoxybenzene sulfonate (OBS)-one of the main alternatives to perfluorooctane sulfonate-has been increasingly detected in both aquatic environments and human bodies. Therefore, the pathogenic risks of OBS exposure warrant attention, especially its central nervous system toxicity mechanism under long-term exposure. In this study, the effects and mechanisms of OBS on the zebrafish brain at 40 days post exposure were examined. The results demonstrated that at 3.2 μg/L, OBS had no significant effect on the zebrafish brain, but 32 μg/L OBS caused depression or poor social behavior in zebrafish and reduced both their memory and survival ability. These changes were accompanied by histological damage and cell apoptosis. Furthermore, OBS caused the accumulation of excessive reactive oxygen species in the fish brain, leading to oxidative stress and subsequently cell apoptosis. Moreover, an imbalance of both inflammatory factors (IL-6, IL-1β, IL-10, TNF-α, and NF-κB) and neurotransmitters (GABA and Glu) led to neuroinflammation. Additionally, 32 μg/L OBS induced decreases in mitochondrial membrane potential and Na+-K+-ATPase activity, leading to both mitochondrial structural damage and the emergence of mitochondrial autophagosomes, partly explaining the neurotoxicity of OBS. These results help to analyze the target sites and molecular mechanisms of OBS neurotoxicity and provide a basis for the scientific evaluation of its health risks to humans.

Neuroligin1 in excitatory synapses contributes to long-term cognitive impairments after repeated neonatal sevoflurane exposures

BACKGROUND

Repeated sevoflurane exposures in neonatal rats may lead to neuronal apoptosis affecting long-term cognitive function, the mechanism is unknown. Neuroligin1 (NL1) is essential for normal excitatory transmission and long-term synaptic plasticity in the hippocampus of intact animals. Herein, we explore the role of NL1 in hippocampal excitatory synapses on long-term cognitive impairments induced by repeated sevoflurane exposures in neonatal rats.

METHODS

From postnatal day six (P6) to P8, neonatal rats were exposed to 30% oxygen or 3% sevoflurane +30% oxygen for 2 h daily. Rats from each litter were randomly assigned to five groups: control group (Con), native control adeno-associated virus (NC-AAV) group (Con + NC-AAV), sevoflurane group (Sev), sevoflurane + recombinant RNAi adeno-associated virus targeting NL1 downregulation (NL1--AAV) group (Sev + NL1--AAV) and control + recombinant RNAi adeno-associated virus targeting NL1 upregulation (NL1+-AAV) group (Con + NL1+-AAV). Animals were injected with NC-AAV or NL1-AAV into the bilateral hippocampal CA1 area and caged on P21. From P35 to P40, behavioral tests including open field (OF), novel object recognition (NOR), and fear conditioning (FC) tests were performed to assess cognitive function in adolescent rats. In another experiment, rat brains were harvested for immunofluorescence staining, western blotting, co-immunoprecipitation, and real-time polymerase chain reaction (PCR).

RESULTS

We found that the mRNA and protein levels of NL1 were substantially higher in the Sev group than in the Con group. Immunofluorescence showed that NL1 and PSD95 were highly colocalized in hippocampal CA1 area and vesicular GABA transporter (vGAT) around neurons decreased after repeated sevoflurane exposures. Co-immunoprecipitation showed that the amount of PSD95 with NL1 antibody was significantly increased in the Sev group compared to the Con group. These rats had a poorer performance in the NOR and FC tests than control rats when they were adolescents. These results were reversed by NL1--AAV injection into the CA1 area. NL1+-AAV group was similar to the Sev group.

CONCLUSION

We have demonstrated that repeated neonatal sevoflurane exposures decreased inhibitory synaptic inputs (labelled by vGAT) around neurons, which may influence the upregulation of NL1 in hippocampal excitatory synapses and enhanced NL1/PSD95 interaction, ultimately leading to long-term cognitive impairments in adolescent rats. Injecting NL1--AAV reversed this damage. These results suggested that NL1 in excitatory synapses contributes to long-term cognitive impairments after repeated neonatal sevoflurane exposures.

Microglia Promote Inhibitory Synapse Phagocytosis in the Spinal Cord Dorsal Horn and Modulate Pain-Like Behaviors in a Murine Cancer-Induced Bone Pain Model

BACKGROUND

The microglial activation has been implicated in cancer-induced bone pain. Recent studies have revealed that microglia mediate synaptic pruning in the central nervous system, where the cluster of differentiation 47-signal regulatory protein α (CD47-SIRPα) axis creates a "don't eat me" signal and elicits an antiphagocytic effect to protect synapses against elimination. To date, the synaptic phagocytosis in microglia has never been investigated in the murine cancer-induced bone pain model. The present experiments sought to explore whether microglia phagocytize synapses in mice with bone cancer pain as well as the possible mechanisms.

METHODS

Male C3H/HeN mice were used to induce bone cancer pain. Minocycline and S-ketamine were injected into D14. The number of spontaneous flinches (NSF) and paw withdrawal mechanical thresholds (PWMT) were measured on D0, D4, D7, D10, D14, D21, and D28. Hematoxylin and eosin staining presented bone lesions. Western blotting examined the Gephyrin, CD47, and SIRPα expression. Flow cytometry evaluated the proportion of SIRPα + cells in the spine. Immunofluorescence and 3-dimensional reconstruction showed the Gephyrin puncta inside microglial lysosomes.

RESULTS

Mice embedded with tumor cells induced persistent spontaneous pain and mechanical hyperalgesia. Hematoxylin and eosin staining revealed bone destruction and tumor infiltration in marrow cavities. Microglia underwent a responsive and proliferative burst (t = -16.831, P < .001). Western blotting manifested lowered Gephyrin expression in the tumor group (D4, D7, D10, D14, D21, and D28: P < .001). Immunofluorescence and 3-dimensional reconstruction showed larger volumes of Gephyrin puncta inside microglial lysosomes (t = -23.273, P < .001; t = -27.997, P < .001). Treatment with minocycline or S-ketamine exhibited pain relief and antiphagocytic effects (t = -6.191, P < .001, t = -7.083, P < .001; t = -20.767, P < .001, t = -17.080, P < .001; t = 11.789, P < .001, t = 16.777, P < .001; t = 8.868, P < .001, t = 21.319, P < .001). Last but not least, the levels of CD47 and SIRPα proteins were downregulated (D10: P = .004, D14, D21, and D28: P < .001; D10, D14, D21, and D28: P < .001). Flow cytometry and immunofluorescence substantiated reduced microglial SIRPα (t = 11.311, P < .001; t = 12.189, P < .001).

CONCLUSIONS

Microglia-mediated GABAergic synapse pruning in the spinal cord dorsal horn in bone cancer pain mice, which might be associated with the declined CD47-SIRPα signal. Our research uncovered an innovative mechanism that highlighted microglia-mediated synaptic phagocytosis in a murine cancer-induced bone pain model.

Contributions of Gamma-Aminobutyric Acid (GABA) Produced by Lactic Acid Bacteria on Food Quality and Human Health: Current Applications and Future Prospects

The need to increase food safety and improve human health has led to a worldwide increase in interest in gamma-aminobutyric acid (GABA), produced by lactic acid bacteria (LABs). GABA, produced from glutamic acid in a reaction catalyzed by glutamate decarboxylase (GAD), is a four-carbon, non-protein amino acid that is increasingly used in the food industry to improve the safety/quality of foods. In addition to the possible positive effects of GABA, called a postbiotic, on neuroprotection, improving sleep quality, alleviating depression and relieving pain, the various health benefits of GABA-enriched foods such as antidiabetic, antihypertension, and anti-inflammatory effects are also being investigated. For all these reasons, it is not surprising that efforts to identify LAB strains with a high GABA productivity and to increase GABA production from LABs through genetic engineering to increase GABA yield are accelerating. However, GABA's contributions to food safety/quality and human health have not yet been fully discussed in the literature. Therefore, this current review highlights the synthesis and food applications of GABA produced from LABs, discusses its health benefits such as, for example, alleviating drug withdrawal syndromes and regulating obesity and overeating. Still, other potential food and drug interactions (among others) remain unanswered questions to be elucidated in the future. Hence, this review paves the way toward further studies.

Repetitive Transcranial Magnetic Stimulation-Mediated Neuroprotection in the 5xFAD Mouse Model of Alzheimer's Disease Through GABRG2 and SNAP25 Modulation

Alzheimer's disease (AD) is a leading neurodegenerative disorder with substantial impacts on cognition and behavior. Repetitive transcranial magnetic stimulation (rTMS), a non-invasive neuromodulation technique, has been used to treat various neuropsychiatric disorders, but its efficacy in AD has not been thoroughly investigated. This study examines the neuroprotective effects of rTMS in the 5xFAD mouse model of AD, with a particular focus on its modulation of GABAergic neuronal activity via the GABRG2 and SNAP25 proteins. Transcriptomic sequencing of rTMS-treated 5xFAD mice revealed 32 genes influenced by the treatment, among which GABRG2 was identified as a critical modulatory target. Electrophysiological assessments, including whole-cell patch clamp recordings from frontal cortex neurons, demonstrated significant alterations in inhibitory synaptic currents following rTMS. Subsequent experiments involved sh-GABRG2 transduction combined with rTMS treatment (20Hz, 14 days), examining behavioral responses, GABAergic neuron functionality, cortical GABA expression, cerebrospinal fluid GABA concentrations, β-amyloid accumulation, and pro-inflammatory cytokine levels. The results indicated notable improvements in behavioral performance, enhanced functionality of GABAergic neurons, and reductions in β-amyloid deposition and neuroinflammation after rTMS treatment. Further analysis revealed that SNAP25 overexpression could counteract the negative effects of GABRG2 silencing, highlighting the crucial role of SNAP25 downstream of GABRG2 in mediating rTMS's therapeutic effects in AD. This research highlights rTMS's potential to modulate synaptic and vesicular transport mechanisms, offering a promising avenue for ameliorating symptoms of AD through neuroprotective pathways.

Investigating the Impacts of Diet, Supplementation, Microbiota, Gut-Brain Axis on Schizophrenia: A Narrative Review

Schizophrenia is a disease with a complex etiology that significantly impairs the functioning of patients. In recent years, there has been increasing focus on the importance of the gut microbiota in the context of the gut-brain axis. In our study, we analyzed data on the gut-brain axis in relation to schizophrenia, as well as the impacts of eating habits, the use of various supplements, and diets on schizophrenia. Additionally, the study investigated the impact of antipsychotics on the development of metabolic disorders, such as diabetes, dyslipidemia, and obesity. There may be significant clinical benefits to be gained from therapies supported by supplements such as omega-3 fatty acids, B vitamins, and probiotics. The results suggest the need for a holistic approach to the treatment of schizophrenia, incorporating both drug therapy and dietary interventions.

Posterior cingulate and medial prefrontal excitation-inhibition balance in euthymic bipolar disorder

BACKGROUND

Persistent cognitive deficits and functional impairments are associated with bipolar disorder (BD), even during the euthymic phase. The dysfunction of default mode network (DMN) is critical for self-referential and emotional mental processes and is implicated in BD. The current study aims to explore the balance of excitatory and inhibitory neurotransmitters, i.e. glutamate and γ-aminobutyric acid (GABA), in hubs of the DMN during the euthymic patients with BD (euBD).

METHOD

Thirty-four euBD and 55 healthy controls (HC) were recruited to the study. Using proton magnetic resonance spectroscopy (1H-MRS), glutamate (with PRESS sequence) and GABA levels (with MEGAPRESS sequence) were measured in the medial prefrontal cortex/anterior cingulate cortex (mPFC/ACC) and the posterior cingulate gyrus (PCC). Measured concentrations of excitatory glutamate/glutamine (Glx) and inhibitory GABA were used to calculate the excitatory/inhibitory (E/I) ratio. Executive and attentional functions were respectively assessed using the Wisconsin card-sorting test and continuous performance test.

RESULTS

euBD performed worse on attentional function than controls (p = 0.001). Compared to controls, euBD had higher E/I ratios in the PCC (p = 0.023), mainly driven by a higher Glx level in the PCC of euBD (p = 0.002). Only in the BD group, a marginally significant negative association between the mPFC E/I ratio (Glx/GABA) and executive function was observed (p = 0.068).

CONCLUSIONS

Disturbed E/I balance, particularly elevated Glx/GABA ratio in PCC is observed in euBD. The E/I balance in hubs of DMN may serve as potential biomarkers for euBD, which may also contribute to their poorer executive function.

Correlation of striatal dopamine D2/3 receptor availability with GABA level in the anterior cingulate cortex in healthy controls but not in alcohol-dependent subjects and individuals at high risk: A multimodal magnetic resonance spectroscopy and positron emission tomography study

BACKGROUND

The association of impaired dopaminergic neurotransmission with the development and maintenance of alcohol use disorder is well known. More specifically, reduced dopamine D2/3 receptors in the striatum of subjects with alcohol dependence (AD) compared to healthy controls have been found in previous studies. Furthermore, alterations of gamma-aminobutyric acid (GABA) and glutamate (Glu) levels in the anterior cingulate cortex (ACC) of AD subjects have been documented in several studies. However, the interaction between cortical Glu levels and striatal dopamine D2/3 receptors has not been investigated in AD thus far.

METHODS

This study investigated dopamine D2/3 receptor availability via 18F-fallypride positron emission tomography (PET) and GABA as well as Glu levels via magnetic resonance spectroscopy (MRS) in 19 detoxified AD subjects, 18 healthy controls (low risk, LR) controls and 19 individuals at high risk (HR) for developing AD, carefully matched for sex, age and smoking status.

RESULTS

We found a significant negative correlation between GABA levels in the ACC and dopamine D2/3 receptor availability in the associative striatum of LR but not in AD or HR individuals. Contrary to our expectations, we did not observe a correlation between Glu concentrations in the ACC and striatal D2/3 receptor availability.

CONCLUSIONS

The results may reflect potential regulatory cortical mechanisms on mesolimbic dopamine receptors and their disruption in AD and individuals at high risk, mirroring complex neurotransmitter interactions associated with the pathogenesis of addiction. This is the first study combining 18F-fallypride PET and MRS in AD subjects and individuals at high risk.

1,2-Dichloroethane causes anxiety and cognitive dysfunction in mice by disturbing GABA metabolism and inhibiting the cAMP-PKA-CREB signaling pathway

1,2-Dichloroethane (1,2-DCE) is a powerfully toxic neurotoxin, which is a common environmental pollutant. Studies have indicated that 1,2-DCE long-term exposure can result in adverse effects. Nevertheless, the precise mechanism remains unknown. In this study, behavioral results revealed that 1,2-DCE long-term exposure could cause anxiety and learning and memory ability impairment in mice. The contents of γ-aminobutyric acid (GABA) and glutamine (Gln) in mice's prefrontal cortex decreased, whereas that of glutamate (Glu) increased. With the increase in dose, the activities of glutamate decarboxylase (GAD) decreased and those of GABA transaminase (GABA-T) increased. The protein and mRNA expressions of GABA transporter-3 (GAT-3), vesicular GABA transporter (VGAT), GABA A receptor α2 (GABAARα2), GABAARγ2, K-Cl cotransporter isoform 2 (KCC2), GABA B receptor 1 (GABABR1), GABABR2, protein kinase A (PKA), cAMP-response element binding protein (CREB), p-CREB, brain-derived neurotrophic factor (BDNF), c-fos, c-Jun and the protein of glutamate dehydrogenase (GDH) and PKA-C were decreased, while the expression levels of GABA transporter-1 (GAT-1) and Na-K-2Cl cotransporter isoform 1 (NKCC1) were increased. However, there was no significant change in the protein content of succinic semialdehyde dehydrogenase (SSADH). The expressions of adenylate cyclase (AC) and cyclic adenosine monophosphate (cAMP) contents were also reduced. In conclusion, the results of this study show that exposure to 1,2-DCE could lead to anxiety and cognitive impairment in mice, which may be related to the disturbance of GABA metabolism and its receptors along with the cAMP-PKA-CREB pathway.

Seeing beyond words: Visualizing autism spectrum disorder biomarker insights

Objective

This study employs bibliometric and visual analysis to elucidate global research trends in Autism Spectrum Disorder (ASD) biomarkers, identify critical research focal points, and discuss the potential integration of diverse biomarker modalities for precise ASD assessment.

Methods

A comprehensive bibliometric analysis was conducted using data from the Web of Science Core Collection database until December 31, 2022. Visualization tools, including R, VOSviewer, CiteSpace, and gCLUTO, were utilized to examine collaborative networks, co-citation patterns, and keyword associations among countries, institutions, authors, journals, documents, and keywords.

Results

ASD biomarker research emerged in 2004, accumulating a corpus of 4348 documents by December 31, 2022. The United States, with 1574 publications and an H-index of 213, emerged as the most prolific and influential country. The University of California, Davis, contributed significantly with 346 publications and an H-index of 69, making it the leading institution. Concerning journals, the Journal of Autism and Developmental Disorders, Autism Research, and PLOS ONE were the top three publishers of ASD biomarker-related articles among a total of 1140 academic journals. Co-citation and keyword analyses revealed research hotspots in genetics, imaging, oxidative stress, neuroinflammation, gut microbiota, and eye tracking. Emerging topics included "DNA methylation," "eye tracking," "metabolomics," and "resting-state fMRI."

Conclusion

The field of ASD biomarker research is dynamically evolving. Future endeavors should prioritize individual stratification, methodological standardization, the harmonious integration of biomarker modalities, and longitudinal studies to advance the precision of ASD diagnosis and treatment.

Evidence from preclinical and clinical metabolomics studies on the antidepressant effects of ketamine and esketamine

The antidepressant effects of ketamine and esketamine are well-documented. Nonetheless, most of the underlying molecular mechanisms have to be uncovered yet. In the last decade, metabolomics has emerged as a useful means to investigate the metabolic phenotype associated with depression as well as changes induced by antidepressant treatments. This mini-review aims at summarizing the main findings from preclinical and clinical studies that used metabolomics to investigate the metabolic effects of subanesthetic, antidepressant doses of ketamine and esketamine and their relationship with clinical response. Both animal and human studies report alterations in several metabolic pathways - including the tricarboxylic acid cycle, glycolysis, the pentose phosphate pathway, lipid metabolism, amino acid metabolism, the kynurenine pathway, and the urea cycle - following the administration of ketamine or its enantiomers. Although more research is needed to clarify commonalities and differences in molecular mechanisms of action between the racemic compound and its enantiomers, these findings comprehensively support an influence of ketamine and esketamine on mitochondrial and cellular energy production, membrane homeostasis, neurotransmission, and signaling. Metabolomics may thus represent a promising strategy to clarify molecular mechanisms underlying treatment-resistant depression and related markers of clinical response to ketamine and esketamine. This body of preclinical and clinical evidence, if further substantiated, has the potential to guide clinicians towards personalized approaches, contributing to new paradigms in the clinical management of depression.

Effect of Ketamine Treatment on Social Withdrawal in Autism and Autism-Like Conditions

OBJECTIVE

Ketamine and esketamine have been used in the field of psychiatry to alleviate conditions such as major depressive disorder. Our objective was to evaluate the current literature on the use of ketamine for symptoms of social withdrawal in autism spectrum disorder (ASD) and autism-like conditions.

METHODS

A comprehensive search of PubMed and Web of Science was conducted to identify literature involving the use of ketamine to treat symptoms of autism and social withdrawal. Patients with comorbid disorders were also included.

RESULTS

Two original studies were found, showing mixed results on the use of ketamine for ASD. The use of esketamine found no statistically significant results, whereas the use of intravenous ketamine was shown to alleviate symptoms of social withdrawal especially in the short term. Neither study reported a significant amount of serious adverse events. Five case reports were also included, showing decreased depressive symptoms and evidence of increased social condition.

CONCLUSIONS

Research on the use of ketamine for ASD and ASD-related conditions is limited. Evidence of improved social condition exists, but further studies should be conducted to increase sample power and test various doses and methods of administration.

Perineuronal nets as regulators of parvalbumin interneuron function: Factors implicated in their formation and degradation

The brain extracellular matrix (ECM) has garnered increasing attention as a fundamental component of brain function in a predominantly "neuron-centric" paradigm. Particularly, the perineuronal nets (PNNs), a specialized net-like structure formed by ECM aggregates, play significant roles in brain development and physiology. PNNs enwrap synaptic junctions in various brain regions, precisely balancing new synaptic formation and long-term stabilization, and are highly dynamic entities that change in response to environmental stimuli, especially during the neurodevelopmental period. They are found mainly surrounding parvalbumin (PV)-expressing GABAergic interneurons, being proposed to promote PV interneuron maturation and protect them against oxidative stress and neurotoxic agents. This structural and functional proximity underscores the crucial role of PNNs in modulating PV interneuron function, which is critical for the excitatory/inhibitory balance and, consequently, higher-level behaviours. This review delves into the molecular underpinnings governing PNNs formation and degradation, elucidating their functional interactions with PV interneurons. In the broader physiological context and brain-related disorders, we also explore their intricate relationship with other molecules, such as reactive oxygen species and metalloproteinases, as well as glial cells. Additionally, we discuss potential therapeutic strategies for modulating PNNs in brain disorders.

Sinapic Acid Mitigates Pentylenetetrazol-induced Acute Seizures By Modulating the NLRP3 Inflammasome and Regulating Calcium/calcineurin Signaling: In Vivo and In Silico Approaches

Sinapic acid (SA) is a naturally occurring carboxylic acid found in citrus fruits and cereals. Recent studies have shown that SA has potential anti-seizure properties due to its anti-inflammatory, antioxidant, and anti-apoptotic effects. The present study investigated the neuroprotective role of SA at two different dosages in a pentylenetetrazol (PTZ)-induced acute seizure model. Mice were divided into six groups: normal control, PTZ, SA (20 mg/kg), SA (20 mg/kg) + PTZ, SA (40 mg/kg), and SA (40 mg/kg) + PTZ. SA was orally administered for 21 days, followed by a convulsive dose of intraperitoneal PTZ (50 mg/kg). Seizures were estimated via the Racine scale, and animals were behaviorally tested using the Y-maze. Brain tissues were used to assess the levels of GABA, glutamate, oxidative stress markers, calcium, calcineurin, (Nod)-like receptor protein-3 (NLRP3), interleukin (IL)-1β, apoptosis-associated speck-like protein (ASC), Bcl-2-associated death protein (Bad) and Bcl-2. Molecular docking of SA using a multistep in silico protocol was also performed. The results showed that SA alleviated oxidative stress, restored the GABA/glutamate balance and calcium/calcineurin signaling, downregulated NLRP3 and apoptosis, and improved recognition and ambulatory activity in PTZ-treated mice. In silico results also revealed that SA strongly interacts with the target proteins NLRP3 and ASC. Overall, the results suggest that SA is a promising antiseizure agent and that both doses of SA are comparable, with 40 mg/kg SA being superior in normalizing glutathione, calcium and IL-1β, in addition to calcineurin, NLRP3, ASC and Bad.

IL-1β, the first piece to the puzzle of sepsis-related cognitive impairment?

Sepsis is a leading cause of death resulting from an uncontrolled inflammatory response to an infectious agent. Multiple organ injuries, including brain injuries, are common in sepsis. The underlying mechanism of sepsis-associated encephalopathy (SAE), which is associated with neuroinflammation, is not yet fully understood. Recent studies suggest that the release of interleukin-1β (IL-1β) following activation of microglial cells plays a crucial role in the development of long-lasting neuroinflammation after the initial sepsis episode. This review provides a comprehensive analysis of the recent literature on the molecular signaling pathways involved in microglial cell activation and interleukin-1β release. It also explores the physiological and pathophysiological role of IL-1β in cognitive function, with a particular focus on its contribution to long-lasting neuroinflammation after sepsis. The findings from this review may assist healthcare providers in developing novel interventions against SAE.

Potential Mechanisms of Casein Hexapeptide YPVEPF on Stress-Induced Anxiety and Insomnia Mice and Its Molecular Effects and Key Active Structure

The hexapeptide YPVEPF with strong sleep-enhancing effects could be detected in rat brain after a single oral administration as we previously proved. In this study, the mechanism and molecular effects of YPVEPF in the targeted stress-induced anxiety mice were first investigated, and its key active structure was further explored. The results showed that YPVEPF could significantly prolong sleep duration and improve the anxiety indexes, including prolonging the time spent in the open arms and in the center. Meanwhile, YPVEPF showed strong sleep-enhancing effects by significantly increasing the level of the GABA/Glu ratio, 5-HT, and dopamine in brain and serum and regulating the anabolism of multiple targets, but the effects could be blocked by bicuculline and WAY100135. Moreover, the molecular simulation results showed that YPVEPF could stably bind to the vital GABAA and 5-HT1A receptors due to the vital structure of Tyr-Pro-Xaa-Xaa-Pro-, and the electrostatic and van der Waals energy played dominant roles in stabilizing the conformation. Therefore, YPVEPF displayed sleep-enhancing and anxiolytic effects by regulating the GABA-Glu metabolic pathway and serotoninergic system depending on distinctive self-folding structures with Tyr and two Pro repeats.

A rate-limiting step in antidepressants onset: Excitation of glutamatergic pyramidal neurons in medial prefrontal cortex of rodents

Although clinical antidepressants have varied mechanisms of action, it remains unclear whether they may have a common mechanism underlying their antidepressant effects. We investigated the behavioral effects of five different antidepressants (differing in target, chemical structure, and rate of onset) and their effects on the firing activities of glutamatergic pyramidal neurons in the medial prefrontal cortex (mPFC) using the forced swimming test (FST) and electrophysiological techniques (in vivo). We employed fiber photometry recordings to validate the effects of antidepressants on the firing activity of pyramidal neurons. Additionally, multichannel electrophysiological recordings were conducted in mice exhibiting depressive-like behaviors induced by chronic restraint stress (CRS) to investigate whether antidepressants exert similar effects on pyramidal neurons in depressed mice. Behavioral tests were utilized for evaluating the depression model. We found that fluoxetine, duloxetine, vilazodone, YL-0919, and ketamine all increase the firing activities of glutamatergic pyramidal neurons (at least 57%) while exerting their initial onset of antidepressant effects. Fiber photometry revealed an increase in the calcium activity of pyramidal neurons in the mPFC at the onset of antidepressant effects. Furthermore, a significant reduction was observed in the firing activity of pyramidal neurons in the mPFC of CRS-exposed mice, which was reversed by antidepressants. Taken together, our findings suggested that five pharmacologically distinct classes of antidepressants share the common ability to increase the firing activity of pyramidal neurons, just different time, which might be a rate-limiting step in antidepressants onset. The study contributes to the body of knowledge of the mechanisms underlying antidepressant effects and paves the way for developing rapid-acting antidepressants.

A new method for isolation and purification of fusion-competent inhibitory synaptic vesicles

Synaptic vesicles specific to inhibitory GABA-releasing neurons are critical for regulating neuronal excitability. To study the specific molecular composition, architecture, and function of inhibitory synaptic vesicles, we have developed a new method to isolate and purify GABA synaptic vesicles from mouse brains. GABA synaptic vesicles were immunoisolated from mouse brain tissue using an engineered fragment antigen-binding region (Fab) against the vesicular GABA transporter (vGAT) and purified. Western blot analysis confirmed that the GABA synaptic vesicles were specifically enriched for vGAT and largely depleted of contaminants from other synaptic vesicle types, such as vesicular glutamate transporter (vGLUT1), and other cellular organelles. This degree of purity was achieved despite the relatively low abundance of vGAT vesicles compared to the total synaptic vesicle pool in mammalian brains. Cryo-electron microscopy images of these isolated GABA synaptic vesicles revealed intact morphology with circular shape and protruding proteinaceous densities. The GABA synaptic vesicles are functional, as assessed by a hybrid (ex vivo/in vitro) vesicle fusion assay, and they undergo synchronized fusion with synthetic plasma membrane mimic vesicles in response to Ca2+-triggering, but, as a negative control, not to Mg2+-triggering. Our immunoisolation method could also be applied to other types of vesicles.

Design and methodology for a proof of mechanism study of individualized neuronavigated continuous Theta burst stimulation for auditory processing in adolescents with autism spectrum disorder

It has been suggested that aberrant excitation/inhibition (E/I) balance and dysfunctional structure and function of relevant brain networks may underlie the symptoms of autism spectrum disorder (ASD). However, the nomological network linking these constructs to quantifiable measures and mechanistically relating these constructs to behavioral symptoms of ASD is lacking. Herein we describe a within-subject, controlled, proof-of-mechanism study investigating the pathophysiology of auditory/language processing in adolescents with ASD. We utilize neurophysiological and neuroimaging techniques including magnetic resonance spectroscopy (MRS), diffusion-weighted imaging (DWI), functional magnetic resonance imaging (fMRI), and magnetoencephalography (MEG) metrics of language network structure and function. Additionally, we apply a single, individually targeted session of continuous theta burst stimulation (cTBS) as an experimental probe of the impact of perturbation of the system on these neurophysiological and neuroimaging outcomes. MRS, fMRI, and MEG measures are evaluated at baseline and immediately prior to and following cTBS over the posterior superior temporal cortex (pSTC), a region involved in auditory and language processing deficits in ASD. Also, behavioral measures of ASD and language processing and DWI measures of auditory/language network structures are obtained at baseline to characterize the relationship between the neuroimaging and neurophysiological measures and baseline symptom presentation. We hypothesize that local gamma-aminobutyric acid (GABA) and glutamate concentrations (measured with MRS), and structural and functional activity and network connectivity (measured with DWI and fMRI), will significantly predict MEG indices of auditory/language processing and behavioral deficits in ASD. Furthermore, a single session of cTBS over left pSTC is hypothesized to lead to significant, acute changes in local glutamate and GABA concentration, functional activity and network connectivity, and MEG indices of auditory/language processing. We have completed the pilot phase of the study (n=20 Healthy Volunteer adults) and have begun enrollment for the main phase with adolescents with ASD (n=86; age 14-17). If successful, this study will establish a nomological network linking local E/I balance measures to functional and structural connectivity within relevant brain networks, ultimately connecting them to ASD symptoms. Furthermore, this study will inform future therapeutic trials using cTBS to treat the symptoms of ASD.

Pharmacokinetics and tissue distribution of vigabatrin enantiomers in rats

Purpose

To investigate the pharmacokinetics and tissue distribution of VGB racemate and its single enantiomers, and explore the potential of clinic development for single enantiomer S-VGB.

Methods

In the pharmacokinetics study, male Sprague-Dawley rats were gavaged with VGB racemate or its single enantiomers dosing 50, 100 or 200 mg/kg, and the blood samples were collected during 12 h at regular intervals. In the experiment of tissue distribution, VGB and its single enantiomers were administered intravenously dosing 200 mg/kg, and the tissues including heart, liver, spleen, lung and kidney, eyes, hippocampus, and prefrontal cortex were separated at different times. The concentrations of R-VGB and S-VGB in the plasma and tissues were measured using HPLC.

Results

Both S-VGB and R-VGB could be detected in the plasma of rats administered with VGB racemate, reaching Cmax at approximately 0.5 h with t1/2 2-3 h. There was no significant pharmacokinetic difference between the two enantiomers when VGB racemate was given 200 mg/kg and 100 mg/kg. However, when given at the dose of 50 mg/kg, S-VGB presented a shorter t1/2 and a higher Cl/F than R-VGB, indicating a faster metabolism of S-VGB. Furthermore, when single enantiomer was administered respectively, S-VGB presented a slower metabolism than R-VGB, as indicated by a longer t1/2 and MRT but a lower Cmax. Moreover, compared with the VGB racemate, the single enantiomers S-VGB and R-VGB had shorter t1/2 and MRT, higher Cmax and AUC/D, and lower Vz/F and Cl/F, indicating the stronger oral absorption and faster metabolism of single enantiomer. In addition, regardless of VGB racemate administration or single enantiomer administration, S-VGB and R-VGB had similar characteristics in tissue distribution, and the content of S-VGB in hippocampus, prefrontal cortex and liver was much higher than that of R-VGB.

Conclusions

Although there is no transformation between S-VGB and R-VGB in vivo, those two enantiomers display certain disparities in the pharmacokinetics and tissue distribution, and interact with each other. These findings might be a possible interpretation for the pharmacological and toxic effects of VGB and a potential direction for the development and optimization of the single enantiomer S-VGB.

The Impact of Genetics on Cognition: Insights into Cognitive Disorders and Single Nucleotide Polymorphisms

This article explores the complex relationship between genetics and cognition, specifically examining the impact of genetic variants, particularly single nucleotide polymorphisms (SNPs), on cognitive functions and the development of neuropsychiatric disorders. Focusing on neurotransmitter regulation within the prefrontal cortex's dopaminergic circuits, this study emphasizes the role of genes like COMT, PRODH, and DRD in shaping executive functions and influencing conditions such as ADHD and schizophrenia. Additionally, it explores the significance of genetic factors in neurodevelopmental disorders, emphasizing the need for early identification to guide appropriate therapeutic interventions. This article also investigates polymorphisms in the transsulfuration pathway, revealing their association with cognitive impairment diseases. Computational analyses, including machine learning algorithms, are highlighted for their potential in predicting symptom severity in ADHD based on genetic variations. In conclusion, this article underscores the intricate interplay of genetic and environmental factors in shaping cognitive outcomes, providing valuable insights for tailored treatments and a more comprehensive understanding of neuropsychiatric conditions.

A comparison between children and adolescents with autism spectrum disorders and healthy controls in biomedical factors, trace elements, and microbiota biomarkers: a meta-analysis

Introduction

Autism spectrum disorder (ASD) is a multifaceted developmental condition that commonly appears during early childhood. The etiology of ASD remains multifactorial and not yet fully understood. The identification of biomarkers may provide insights into the underlying mechanisms and pathophysiology of the disorder. The present study aimed to explore the causes of ASD by investigating the key biomedical markers, trace elements, and microbiota factors between children with autism spectrum disorder (ASD) and control subjects.

Methods

Medline, PubMed, ProQuest, EMBASE, Cochrane Library, PsycINFO, Web of Science, and EMBSCO databases have been searched for publications from 2012 to 2023 with no language restrictions using the population, intervention, control, and outcome (PICO) approach. Keywords including "autism spectrum disorder," "oxytocin," "GABA," "Serotonin," "CRP," "IL-6," "Fe," "Zn," "Cu," and "gut microbiota" were used for the search. The Joanna Briggs Institute (JBI) critical appraisal checklist was used to assess the article quality, and a random model was used to assess the mean difference and standardized difference between ASD and the control group in all biomedical markers, trace elements, and microbiota factors.

Results

From 76,217 records, 43 studies met the inclusion and exclusion criteria and were included in this meta-analysis. The pooled analyses showed that children with ASD had significantly lower levels of oxytocin (mean differences, MD = -45.691, 95% confidence interval, CI: -61.667, -29.717), iron (MD = -3.203, 95% CI: -4.891, -1.514), and zinc (MD = -6.707, 95% CI: -12.691, -0.722), lower relative abundance of Bifidobacterium (MD = -1.321, 95% CI: -2.403, -0.238) and Parabacteroides (MD = -0.081, 95% CI: -0.148, -0.013), higher levels of c-reactive protein, CRP (MD = 0.401, 95% CI: 0.036, 0.772), and GABA (MD = 0.115, 95% CI: 0.045, 0.186), and higher relative abundance of Bacteroides (MD = 1.386, 95% CI: 0.717, 2.055) and Clostridium (MD = 0.281, 95% CI: 0.035, 0.526) when compared with controls. The results of the overall analyses were stable after performing the sensitivity analyses. Additionally, no substantial publication bias was observed among the studies.

Interpretation

Children with ASD have significantly higher levels of CRP and GABA, lower levels of oxytocin, iron, and zinc, lower relative abundance of Bifidobacterium and Parabacteroides, and higher relative abundance of Faecalibacterium, Bacteroides, and Clostridium when compared with controls. These results suggest that these indicators may be a potential biomarker panel for the diagnosis or determining therapeutic targets of ASD. Furthermore, large, sample-based, and randomized controlled trials are needed to confirm these results.

Advances in steroid research from the pioneering neurosteroid concept to metabolomics: New insights into pregnenolone function

Advances in neuroendocrinology have led to major discoveries since the 19th century, identifying adaptive loops for maintaining homeostasis. One of the most remarkable discoveries was the concept of neurosteroids, according to which the brain is not only a target but also a source of steroid production. The identification of new membrane steroid targets now underpins the neuromodulatory effects of neurosteroids such as pregnenolone, which is involved in functions mediated by the GPCR CB1 receptor. Structural analysis of steroids is a key feature of their interactions with the phospholipid membrane, receptors and resulting activity. Therefore, mass spectrometry-based methods have been developed to elucidate the metabolic pathways of steroids, the ultimate approach being metabolomics, which allows the identification of a large number of metabolites in a single sample. This approach should enable us to make progress in understanding the role of neurosteroids in the functioning of physiological and pathological processes.

Interplay of G-proteins and Serotonin in the Neuroimmunoinflammatory Model of Chronic Stress and Depression: A Narrative Review

INTRODUCTION

This narrative review addresses the clinical challenges in stress-related disorders such as depression, focusing on the interplay between neuron-specific and pro-inflammatory mechanisms at the cellular, cerebral, and systemic levels.

OBJECTIVE

We aim to elucidate the molecular mechanisms linking chronic psychological stress with low-grade neuroinflammation in key brain regions, particularly focusing on the roles of G proteins and serotonin (5-HT) receptors.

METHODS

This comprehensive review of the literature employs systematic, narrative, and scoping review methodologies, combined with systemic approaches to general pathology. It synthesizes current research on shared signaling pathways involved in stress responses and neuroinflammation, including calcium-dependent mechanisms, mitogen-activated protein kinases, and key transcription factors like NF-κB and p53. The review also focuses on the role of G protein-coupled neurotransmitter receptors (GPCRs) in immune and pro-inflammatory responses, with a detailed analysis of how 13 of 14 types of human 5-HT receptors contribute to depression and neuroinflammation.

RESULTS

The review reveals a complex interaction between neurotransmitter signals and immunoinflammatory responses in stress-related pathologies. It highlights the role of GPCRs and canonical inflammatory mediators in influencing both pathological and physiological processes in nervous tissue.

CONCLUSION

The proposed Neuroimmunoinflammatory Stress Model (NIIS Model) suggests that proinflammatory signaling pathways, mediated by metabotropic and ionotropic neurotransmitter receptors, are crucial for maintaining neuronal homeostasis. Chronic mental stress can disrupt this balance, leading to increased pro-inflammatory states in the brain and contributing to neuropsychiatric and psychosomatic disorders, including depression. This model integrates traditional theories on depression pathogenesis, offering a comprehensive understanding of the multifaceted nature of the condition.

Targeting mGluR group III for the treatment of neurodegenerative diseases

Glutamate, an excitatory neurotransmitter, is essential for neuronal function, and it acts on ionotropic or metabotropic glutamate receptors (mGluRs). A disturbance in glutamatergic signaling is a hallmark of many neurodegenerative diseases. Developing disease-modifying treatments for neurodegenerative diseases targeting glutamate receptors is a promising avenue. The understudied group III mGluR 4, 6-8 are commonly found in the presynaptic membrane, and their activation inhibits glutamate release. Thus, targeted mGluRs therapies could aid in treating neurodegenerative diseases. This review describes group III mGluRs and their pharmacological ligands in the context of amyotrophic lateral sclerosis, Parkinson's, Alzheimer's, and Huntington's diseases. Attempts to evaluate the efficacy of these drugs in clinical trials are also discussed. Despite a growing list of group III mGluR-specific pharmacological ligands, research on the use of these drugs in neurodegenerative diseases is limited, except for Parkinson's disease. Future efforts should focus on delineating the contribution of group III mGluR to neurodegeneration and developing novel ligands with superior efficacy and a favorable side effect profile for the treatment of neurodegenerative diseases.

Changes in the Glutamate/GABA System in the Hippocampus of Rats with Age and during Alzheimer's Disease Signs Development

GABA and glutamate are the most abundant neurotransmitters in the CNS and play a pivotal part in synaptic stability/plasticity. Glutamate and GABA homeostasis is important for healthy aging and reducing the risk of various neurological diseases, while long-term imbalance can contribute to the development of neurodegenerative disorders, including Alzheimer's disease (AD). Normalization of the homeostasis has been discussed as a promising strategy for prevention and/or treatment of AD, however, data on the changes in the GABAergic and glutamatergic systems with age, as well as on the dynamics of AD development, are limited. It is not clear whether imbalance of the excitatory/inhibitory systems is the cause or the consequence of the disease development. Here we analyzed the age-related alterations of the levels of glutamate, GABA, as well as enzymes that synthesize them (glutaminase, glutamine synthetase, GABA-T, and GAD67), transporters (GLAST, GLT-1, and GAT1), and relevant receptors (GluA1, NMDAR1, NMDA2B, and GABAAr1) in the whole hippocampus of the Wistar rats and of the senescence-accelerated OXYS rats, a model of the most common (> 95%) sporadic AD. Our results suggest that there is a decline in glutamate and GABA signaling with age in hippocampus of the both rat strains. However, we have not identified significant changes or compensatory enhancements in this system in the hippocampus of OXYS rats during the development of neurodegenerative processes that are characteristic of AD.

NMR metabolomics study of chronic low-dose exposure to a cocktail of persistent organic pollutants

Nowadays, exposure to endocrine-disrupting chemicals (EDCs), including persistent organic pollutants (POPs), is one of the most critical threats to public health. EDCs are chemicals that mimic, block, or interfere with hormones in the body's endocrine system and have been associated with a wide range of health issues. This innovative, untargeted metabolomics study investigates chronic low-dose internal exposure to a cocktail of POPs on multiple tissues that are known to accumulate these lipophilic compounds. Interestingly, the metabolic response differs among selected tissues/organs in mice. In the liver, we observed a dynamic effect according to the exposure time and the doses of POPs. In the brain tissue, the situation is the opposite, leading to the conclusion that the presence of POPs immediately gives a saturated effect that is independent of the dose and the duration of exposure studied. By contrast, for the adipose tissues, nearly no effect is observed. This metabolic profiling leads to a holistic and dynamic overview of the main metabolic pathways impacted in lipophilic tissues by a cocktail of POPs.

Diazepam effects on anxiety-related defensive behavior of male and female high and low open-field activity inbred mouse strains

Open-field activity is a commonly used measure of anxiety-related behavior in rodents. The inbred High and Low Activity strains of mice, selected for extreme differences in open-field activity, have been used as a genetic model of anxiety-related behaviors. These selected strains have been thoroughly studied through extensive behavioral testing, quantitative trait locus (QTL) mapping, whole-genome sequencing, and RNA sequencing, to uncover phenotypic and genotypic differences related to anxiety-related behavior. However, the effects of anxiolytic drugs on anxiety-related behavior in these strains have not been studied previously. This study allowed us to expand on previous findings to further characterize the anxiety-related behavior of these unique strains, using an anxiolytic drug. The goal of this study was to determine whether the treatment of adult male and female High Activity (low anxiety) and Low Activity (high anxiety) mice with diazepam, an agonist at the benzodiazepine allosteric site on the GABAA receptor and a drug commonly prescribed to treat anxiety disorders in humans, led to decreases in anxiety-like defensive behavioral responses as assessed in the open-field test (OFT) and elevated plus-maze (EPM). We tested the effects of three doses of diazepam (0, 0.5, 1.0, 3.0 mg/kg, i.p.), given 30 min before behavioral testing to one High Activity strain (H2) and two Low Activity strains (L1 and L2). There was an anxiolytic effect of diazepam observed in the High Activity strain, with more entries into the open arms of the elevated plus-maze, an effect similar to that seen in common mouse strains. However, the only anxiolytic effect of diazepam seen in the Low Activity strains was a reduction in stretch attend posture (SAP). Low Activity strains also displayed freezing behavior in both the OFT and EPM. The combination of the observed freezing behavior, that was not reduced by diazepam, and the reduction in SAP seen with diazepam, suggests a more complex phenotype that includes a component of innate fear in addition to anxiety-related risk assessment behaviors. Since fear and anxiety are distinguishable traits, and both contribute to human anxiety disorders, these results provide novel insight about interpretation of previous genetic and phenotypic differences observed between the High and Low Activity strains.

Kynurenine, Kynurenic Acid, Quinolinic Acid and Interleukin-6 Levels in the Serum of Patients with Autism Spectrum Disorder

Background and Objectives: It is known that inflammatory processes play a role in the pathogenesis of autism spectrum disorder (ASD). It is also reported that immune activation induces the kynurenine pathway (KP), as known as the tryptophan destruction pathway. In our study, we aimed to investigate whether the serum levels of KP products and interleukin (IL)-6 activating indolamine 2-3 dioxygenase (IDO) enzyme are different in healthy developing children and children with ASD. Materials and Methods: Forty-three ASD children aged 2-9 were included in this study. Forty-two healthy developing children, similar to the patient group in terms of age and gender, were selected as the control group. Serum levels of kynurenic acid, kynurenine, quinolinic acid and IL-6 were analyzed using the ELISA method. ASD severity was evaluated with the Autism Behavior Checklist (ABC). Results: The mean age of children with ASD was 42.4 ± 20.5 months, and that of healthy controls was 48.1 ± 15.8 months. While the serum levels of kynurenic acid, kynurenine and interleukin-6 were higher in the group with ASD (p < 0.05), there was no significant difference (p > 0.05) in terms of the quinolinic acid level. There was no significant difference between the ABC total and subscale scores of children with ASD and biochemical parameters (p > 0.05). Conclusions: We conclude that these biomarkers must be measured in all ASD cases. They may be important for the diagnosis of ASD.

Pterostilbene as a Therapeutic Alternative for Central Nervous System Disorders: A Review of the Current Status and Perspectives

Neurological disorders are diverse, have complex causes, and often result in disability; yet, effective treatments remain scarce. The resveratrol derivative pterostilbene possesses numerous physiological activities that hold promise as a novel therapy for the central nervous system (CNS) disorders. This review aimed to summarize the protective mechanisms of pterostilbene in in vitro and in vivo models of CNS disorders and the pharmacokinetics and safety to assess its possible effects on CNS disorders. Available evidence supports the protective effects of pterostilbene in CNS disorders involving mechanisms such as antioxidant and anti-inflammatory activity, regulation of lipid metabolism and vascular smooth muscle cell proliferation, improvement of synaptic function and neurogenesis, induction of glioma cell cycle arrest, and inhibition of glioma cell migration and invasion. Studies have identified possible molecular targets and pathways for the protective actions of pterostilbene in CNS disorders including the AMPK/STAT3, Akt, NF-κB, MAPK, and ERK signaling pathways. The possible pharmacological effects and molecular pathways of pterostilbene in CNS disorders are critically discussed in this review. Future studies should aim to increase our understanding of pterostilbene in animal models and humans to further evaluate its role in CNS disorders and the detailed mechanisms.

The Relationship between Retained Primitive Reflexes and Hemispheric Connectivity in Autism Spectrum Disorders

BACKGROUND

Autism Spectrum Disorder (ASD) can be identified by a general tendency toward a reduction in the expression of low-band, widely dispersed integrative activities, which is made up for by an increase in localized, high-frequency, regionally dispersed activity. The study assessed ASD children and adults all possessing retained primitive reflexes (RPRs) compared with a control group that did not attempt to reduce or remove those RPRs and then examined the effects on qEEG and brain network connectivity.

METHODS

Analysis of qEEG spectral and functional connectivity was performed, to identify associations with the presence or absence of retained primitive reflexes (RPRs), before and after an intervention based on TENS unilateral stimulation.

RESULTS

The results point to abnormal lateralization in ASD, including long-range underconnectivity, a greater left-over-right qEEG functional connectivity ratio, and short-range overconnectivity in ASD.

CONCLUSIONS

Clinical improvement and the absence of RPRs may be linked to variations in qEEG frequency bands and more optimized brain networks, resulting in more developmentally appropriate long-range connectivity links, primarily in the right hemisphere.

Decreased GABA+ ratios referenced to creatine and phosphocreatine in the left dorsolateral prefrontal cortex of females of reproductive age with major depression

BACKGROUND

It has been suggested that the dorsolateral prefrontal cortex (DLPFC), especially the left DLPFC, has an important role in the pathophysiology and the treatment of major depressive disorder (MDD); furthermore, the contributory and antidepressant role of γ-aminobutyric acid (GABA) is increasingly recognized. Given that most female patients with MDD are of reproductive age, we sought to assess in vivo baseline GABA levels in the left DLPFC among unmedicated females of reproductive age with depression.

METHODS

We compared healthy females and females with MDD. Both groups were of reproductive age. We confirmed absence of current or past psychiatric diagnosis among healthy controls or a current diagnosis of MDD via a structured interview. We measured GABA+ (including homocarnosine and macromolecules), referenced to creatine and phosphocreatine, via magnetic resonance spectroscopy using a 3 Tesla magnet.

RESULTS

We included 20 healthy controls and 13 participants with MDD. All participants were unmedicated at the time of the study. All females were scanned during the early follicular phase of the menstrual cycle. Levels of GABA+ in the left DLPFC were significantly lower among participants with MDD (median 0.08) than healthy controls (median 0.10; U = 66.0, p = 0.02, r = 0.41).

LIMITATIONS

When we adjusted for fit error as a covariate, we lost statistical significance for left DLPFC GABA+. However, when we adjusted for signal-to-noise ratio, statistical significance was maintained.

CONCLUSION

Our results suggest that GABA+ levels in the left DLPFC may vary by depression status and should be examined as a possible treatment target.

Neurometabolite levels in the brains of patients with autism spectrum disorders: A meta-analysis of proton magnetic resonance spectroscopy studies (N = 1501)

Evidence suggests that neurometabolite alterations may be involved in the pathophysiology of autism spectrum disorders (ASDs). We performed a meta-analysis of proton magnetic resonance spectroscopy (1H-MRS) studies to examine the neurometabolite levels in the brains of patients with ASD. A systematic search of PubMed and Web of Science identified 54 studies for the meta-analysis. A random-effects meta-analysis demonstrated that compared with the healthy controls, patients with ASD had lower N-acetyl-aspartate-containing compound (NAA) and choline-containing compound (Cho) levels and NAA/(creatine-containing compound) Cr ratios in the gray matter and lower NAA and glutamate + glutamine (Glx) levels in the white matter. Furthermore, NAA and gamma-aminobutyric acid (GABA) levels, NAA/Cr ratios, and GABA/Cr ratios were significantly decreased in the frontal cortex of patients with ASD, whereas glutamate (Glu) levels were increased in the prefrontal cortex. Additionally, low NAA levels and GABA/Cr ratios in the temporal cortex, low NAA levels and NAA/Cr ratios in the parietal and dorsolateral prefrontal cortices, and low NAA levels in the cerebellum and occipital cortex were observed in patients with ASD. Meta-regression analysis revealed that age was positively associated with effect size in studies analyzing the levels of gray matter NAA and white matter Glx. Taken together, these results provide strong clinical evidence that neurometabolite alterations in specific brain regions are associated with ASD and age is a confounding factor for certain neurometabolite levels in patients with ASD.

Understanding the initiation, delivery and processing of bone cancer pain from the peripheral to the central nervous system

Bone cancer pain is a complex condition characterized by persistent, sudden, spontaneous pain accompanied by hyperalgesia that typically arises from bone metastases or primary bone tumors, causing severe discomfort and significantly diminishing cancer patients' quality of life and confidence in their ability to overcome the disease. It is widely known that peripheral nerves are responsible for detecting harmful stimuli, which are then transmitted to the brain via the spinal cord, resulting in the perception of pain. In the case of bone cancer, tumors and stromal cells within the bone marrow release various chemical signals, including inflammatory factors, colony-stimulating factors, chemokines, and hydrogen ions. Consequently, the nociceptors located at the nerve endings within the bone marrow sense these chemical signals, generating electrical signals that are then transmitted to the brain through the spinal cord. Subsequently, the brain processes these electrical signals in a complex manner to create the sensation of bone cancer pain. Numerous studies have investigated the transmission of bone cancer pain from the periphery to the spinal cord. However, the processing of pain information induced by bone cancer within the brain remains unclear. With the continuous advancements in brain science and technology, the brain mechanism of bone cancer pain would become more clearly understood. Herein, we focus on summarizing the peripheral nerve perception of the spinal cord transmission of bone cancer pain and provide a brief overview of the ongoing research regarding the brain mechanisms involved in bone cancer pain.

Syntabulin regulates neuronal excitation/inhibition balance and epileptic seizures by transporting syntaxin 1B

Epilepsy is a widespread neurological disorder affecting more than 65 million people, but the mechanisms of epilepsy remains unknown. Abnormal synaptic transmission has a crucial role in the occurrence and development of epilepsy. Here, we found that syntabulin, a neuronal transporter, was mainly localized in neurons, and its expression was increased in epileptic tissues. Knockdown of syntabulin increased susceptibility and severity of epilepsy, whereas overexpression of syntabulin had the opposite effect. Mechanistically, in the epileptic brain tissue, syntabulin mainly translocated syntaxin 1B (STX1B) rather than syntaxin 1A (STX1A) to the presynaptic membrane, which resulted in increased presynaptic transmitter release. Further studies showed that syntabulin had a more significant effect on presynaptic functionality of GABAergic activity over that of excitatory synapses and resulted in an excitation/inhibition (E/I) imbalance, thereby regulating the epileptic phenotype. In addition, we found that the increased expression of syntabulin in epileptic brain tissue was mainly regulated by transcription factor TFAP2A. In summary, syntabulin plays a protective role in epilepsy by maintaining a proper E/I balance in the hippocampus.

γ-Aminobutyric acid as a biomarker of the lateralizing and monitoring drug effect in patients with magnetic resonance imaging-negative temporal lobe epilepsy

Introduction

Despite verifying proton magnetic resonance spectroscopy (¹H-MRS) for focal localization in magnetic resonance imaging (MRI)-negative temporal lobe epilepsy (TLE), it is necessary to illustrate metabolic changes and screen for effective biomarkers for monitoring therapeutic effect. We used ¹H-MRS to investigate the role of metabolic levels in MRI-negative TLE.

Materials and methods

Thirty-seven patients (n = 37, 14 women) and 20 healthy controls (n = 20, 11 women) were investigated by ¹H-MRS. We compared the metabolite level changes in the epileptic and contralateral sides on the mesial temporal and dorsolateral prefrontal cortices and analyzed their association with clinical symptoms.

Results

γ-Aminobutyric acid (GABA) levels were significantly lower on the epileptic side (2.292 ± 0.890) than in the contralateral side (2.662 ± 0.742, p = 0.029*) in patients on the mesial temporal lobe. N-acetylaspartate (NAA) levels were significantly lower on the epileptic side (7.284 ± 1.314) than on the contralateral side (7.655 ± 1.549, p = 0.034*). NAA + N-acetylaspartylglutamate levels were significantly lower on the epileptic side (7.668 ± 1.406) than on the contralateral side (8.086 ± 1.675, p = 0.032*). Glutamate levels were significantly lower on the epileptic side (7.773 ± 1.428) than on the contralateral side (8.245 ± 1.616, p = 0.040*). Moreover, a significant negative correlation was found between GABA levels in the epileptic mesial temporal lobe and tonic-clonic seizure frequency (r = -0.338, p = 0.046*).

Conclusion

γ-Aminobutyric acid (GABA) is a potential biomarker for lateralization and monitoring seizure frequency in MRI-negative TLE.

Association between methylation in the promoter region of the GAD2 gene and opioid use disorder

DNA methylation is one of the epigenetic mechanisms involved in opioid use disorder. GAD2 is a key catalyticase in gamma amino butyric acid (GABA) synthesis from glutamate, that is implicated in opioid-induced rewarding effect. To reveal the relationship and the underlying mechanism between GAD2 gene methylation and opioid use disorder, we first examined and compared the methylation levels in the promoter region of the GAD2 gene in peripheral blood between 120 patients with opioid use disorder and 110 healthy controls by using a targeted approach. A diagnostic model with methylation biomarkers was established to distinguish opioid use disorder and healthy control groups. Correlations between methylation levels in the promoter region of the GAD2 gene and the duration and dosage of opioid use were then determined. Finally, the transcription factors that potentially bind to the target sequences including the detected CpG sites were predicted with the JASPAR database. Our results demonstrated that hypermethylation in the promoter region of the GAD2 gene was associated with opioid use disorder. A diagnostic model based on 10 methylation biomarkers could distinguish the opioid use disorder and healthy control groups. Several correlations between methylation levels in the GAD2 gene promoter and the duration and dosage of opioid use were observed. Transcription factors TFAP2A, Arnt and Runx1 were predicted to bind to the target sequences including several CpG sites detected in the present study in the GAD2 gene promoter. Our findings highlight and extend the role of DNA methylation in the GAD2 gene in opioid use disorder.

Time-resolved correlation of distributed brain activity tracks E-I balance and accounts for diverse scale-free phenomena

Much of systems neuroscience posits the functional importance of brain activity patterns that lack natural scales of sizes, durations, or frequencies. The field has developed prominent, and sometimes competing, explanations for the nature of this scale-free activity. Here, we reconcile these explanations across species and modalities. First, we link estimates of excitation-inhibition (E-I) balance with time-resolved correlation of distributed brain activity. Second, we develop an unbiased method for sampling time series constrained by this time-resolved correlation. Third, we use this method to show that estimates of E-I balance account for diverse scale-free phenomena without need to attribute additional function or importance to these phenomena. Collectively, our results simplify existing explanations of scale-free brain activity and provide stringent tests on future theories that seek to transcend these explanations.

The roles of neuroinflammation and glutamatergic excitotoxicity in treatment-resistant depression

ABSTRACT

Major depressive disorder affects nearly 20% of people during their lifetime. A growing body of evidence supports the theory that neuroinflammation plays a prominent role in the neurobiology of depression, which implicates glutamate and gamma aminobutyric acid as key factors in the pathophysiology of the disease process. This article reviews the pathologic pathways of glutamate excess in the central nervous system and how they may be implicated in the underlying disorder of treatment-resistant depression and targeted for treatment.

Effects of common antiepileptic drugs on teleost fishes

Antiepileptic drugs (AEDs) are globally prescribed to treat epilepsy and many other psychiatric disorders in humans. Their high consumption, low metabolic rate in the human body and low efficiency of wastewater treatment plants (WWTPs) in eliminating these chemicals results in the frequent occurrence of these pharmaceutical drugs in aquatic systems. Therefore, aquatic organisms, including ecologically and economically important teleost fishes, may be inadvertently exposed to these chemicals. Due to their physiological similarity with humans, fishes may be particularly vulnerable to AEDs. Almost all AED drugs are detectable in natural aquatic ecosystems, but diazepam (DZP) and carbamazepine (CBZ) are among the most widely detected AEDs to date. Recent studies suggest that these drugs have a substantial capacity to induce neurotoxicity and behavioral abnormality in fishes. Here we review the current state of knowledge regarding the potential mode of action of DZP and CBZ as well as that of some other AEDs on teleosts and put observable behavioral effects into a mechanistic context. We find that following their intended mode of action in humans, AEDs also disrupt the GABAergic, glutamatergic and serotonergic systems as well as parasympathetic neurotransmitters in fishes. Moreover, AEDs have non-specific modes of action in teleosts ranging from estrogenic activity to oxidative stress. These physiological changes are often accompanied by dose-dependent disruptions of anxiety, locomotor activity, social behaviors, food uptake, and learning and memory, but DZP and CBZ consistently induced anxiolytic effects. Thereby, AED exposure severely compromises individual fitness across teleost fish species, which may lead to population and ecosystem impairment. We also showcase promising avenues for future research by highlighting where we lack data when it comes to effects of certain AEDs, AED concentrations and behavioral endpoints.

Revealing the neurobiology underlying interpersonal neural synchronization with multimodal data fusion

Humans synchronize with one another to foster successful interactions. Here, we use a multimodal data fusion approach with the aim of elucidating the neurobiological mechanisms by which interpersonal neural synchronization (INS) occurs. Our meta-analysis of 22 functional magnetic resonance imaging and 69 near-infrared spectroscopy hyperscanning experiments (740 and 3721 subjects) revealed robust brain regional correlates of INS in the right temporoparietal junction and left ventral prefrontal cortex. Integrating this meta-analytic information with public databases, biobehavioral and brain-functional association analyses suggested that INS involves sensory-integrative hubs with functional connections to mentalizing and attention networks. On the molecular and genetic levels, we found INS to be associated with GABAergic neurotransmission and layer IV/V neuronal circuits, protracted developmental gene expression patterns, and disorders of neurodevelopment. Although limited by the indirect nature of phenotypic-molecular association analyses, our findings generate new testable hypotheses on the neurobiological basis of INS.

Identification of a Novel Idiopathic Epilepsy Risk Locus and a Variant in the CCDC85A Gene in the Dutch Partridge Dog

(1) Idiopathic epilepsy (IE) is thought to have a genetic cause in several dog breeds. However, only two causal variants have been identified to date, and few risk loci are known. No genetic studies have been conducted on IE in the Dutch partridge dog (DPD), and little has been reported on the epileptic phenotype in this breed. (2) Owner-filled questionnaires and diagnostic investigations were used to characterize IE in the DPD. A genome-wide association study (GWAS) involving 16 cases and 43 controls was performed, followed by sequencing of the coding sequence and splice site regions of a candidate gene within the associated region. Subsequent whole-exome sequencing (WES) of one family (including one IE-affected dog, both parents, and an IE-free sibling) was performed. (3) IE in the DPD has a broad range in terms of age at onset, frequency, and duration of epileptic seizures. Most dogs showed focal epileptic seizures evolving into generalized seizures. A new risk locus on chromosome 12 (BICF2G630119560; p_raw = 4.4 × 10^-7; p_adj = 0.043) was identified through GWAS. Sequencing of the GRIK2 candidate gene revealed no variants of interest. No WES variants were located within the associated GWAS region. However, a variant in CCDC85A (chromosome 10; XM_038680630.1: c.689C > T) was discovered, and dogs homozygous for the variant (T/T) had an increased risk of developing IE (OR: 6.0; 95% CI: 1.6-22.6). This variant was identified as likely pathogenic according to ACMG guidelines. (4) Further research is necessary before the risk locus or CCDC85A variant can be used for breeding decisions.

NMDA Receptor Activation and Ca2+/PKC Signaling in Nicotine-Induced GABA Transport Shift in Embryonic Chick Retina

Nicotinic receptors are present in the retina of different vertebrates, and in the chick retina, it is present during early development throughout to post-hatching. These receptors are activated by nicotine, an alkaloid with addictive and neurotransmitter release modulation properties, such as GABA signaling. Here we evaluated the mechanisms of nicotine signaling in the avian retina during the development of neuron-glia cells at a stage where synapses are peaking. Nicotine almost halved [³H]-GABA uptake, reducing it by 45% whilst increasing more than two-fold [³H]-GABA release in E12 embryonic chick retinas. Additionally, nicotine mediated a 33% increase in [³H]-D-aspartate release. MK-801 50 μM blocked 66% of nicotine-induced [³H]-GABA release and Gö 6983 100 nM prevented the nicotine-induced reduction in [³H]-GABA uptake by rescuing 40% of this neurotransmitter uptake, implicating NMDAR and PKC (respectively) in the nicotinic responses. In addition, NO-711 prevented [³H]-GABA uptake and release induced by nicotine. Furthermore, the relevance of calcium influx for PKC activation was evidenced through fura-2 imaging. We conclude that the shift of GABA transport mediated by nicotine promotes GABA release by inducing transporter reversal via nicotine-induced EAA release through EAATs, or by a direct effect of nicotine in activating nicotinic receptors permeable to calcium and promoting PKC pathway activation and shifting GAT-1 activity, both prompting calcium influx, and activation of the PKC pathway and shifting GAT-1 activity.

Cholesterol metabolism pathway in autism spectrum disorder: From animal models to clinical observations

Autism Spectrum Disorder (ASD) is a neurodevelopmental disorder characterized by a persistent impairment of social skills, including aspects of perception, interpretation, and response, combined with restricted and repetitive behavior. ASD is a complex and multifactorial condition, and its etiology could be attributed to genetic and environmental factors. Despite numerous clinical and experimental studies, no etiological factor, biomarker, and specific model of transmission have been consistently associated with ASD. However, an imbalance in cholesterol levels has been observed in many patients, more specifically, a condition of hypocholesterolemia, which seems to be shared between ASD and ASD-related genetic syndromes such as fragile X syndrome (FXS), Rett syndrome (RS), and Smith- Lemli-Opitz (SLO). Furthermore, it is known that alterations in cholesterol levels lead to neuroinflammation, oxidative stress, impaired myelination and synaptogenesis. Thus, the aim of this review is to discuss the cholesterol metabolic pathways in the ASD context, as well as in genetic syndromes related to ASD, through clinical observations and animal models. In fact, SLO, FXS, and RS patients display early behavioral markers of ASD followed by cholesterol disturbances. Several studies have demonstrated the role of cholesterol in psychiatric conditions and how its levels modulate brain neurodevelopment. This review suggests an important relationship between ASD pathology and cholesterol metabolism impairment; thus, some strategies could be raised - at clinical and pre-clinical levels - to explore whether cholesterol metabolism disturbance has a generally adverse effect in exacerbating the symptoms of ASD patients.