Genetic polymorphism of glutathione S-transferases: Relevance to neurological disorders

Exposure to nickel chloride induces epigenetic modification on detoxification enzyme glutathione S-transferase M2

Nickel (Ni) is a human carcinogen with genotoxic and epigenotoxic effects. Environmental and occupational exposure to Ni increases the risk of cancer and chronic inflammatory diseases. Our previous findings indicate that Ni alters gene expression through epigenetic regulation, specifically impacting E-cadherin and angiopoietin-like 4 (ANGPTL4), involved in epithelial-mesenchymal transition and migration. GST-M2, a member of the glutathione S-transferase (GST) enzyme family, plays a crucial role in cellular defense against oxidative damage and has been increasingly associated with cancer. GST-M2 overexpression inhibits lung cancer invasion and metastasis in vitro and in vivo. Hypermethylation of its promoter in cancer cells reduces gene expression, correlating with poor prognosis in non-small-cell lung cancer patients. The impact of Ni on GST-M2 remains unclear. We will investigate whether nickel exerts regulatory effects on GST-M2 through epigenetic modifications. Additionally, metformin, an antidiabetic drug, is being studied as a chemopreventive agent against nickel-induced damage. Our findings indicate that nickel chloride (NiCl2 ) exposure, both short-term and long-term, represses GST-M2 expression. However, the expression can be restored by demethylation agent 5-aza-2'-deoxycytidine and metformin. NiCl2 promotes hypermethylation of the GST-M2 promoter, as confirmed by methylation-specific PCR and bisulfite sequencing. Additionally, NiCl2 also influences histone acetylation, and metformin counteracts the suppressive effect of NiCl2 on histone H3 expression. Metformin reestablishes the binding of specificity protein 1 to the GST-M2 promoter, which is otherwise disrupted by NiCl2 . These findings elucidate the mechanism by which Ni reduces GST-M2 expression and transcriptional activity, potentially contributing to Ni-induced lung carcinogenesis.

The susceptibility of humans to neurodegenerative and neurodevelopmental toxicities caused by organophosphorus pesticides

The toxicology field is concerned with the impact of organophosphorus (OP) compounds on human health. These compounds have been linked to an increased risk of neurological disorders, including neurodegenerative and neurodevelopmental diseases. This article aims to review studies on the role of OP compounds in developing these neurological disorders and explore how genetic variations can affect susceptibility to the neurotoxicity of these pesticides. Studies have shown that exposure to OP compounds can lead to the development of various neurological disorders, such as Alzheimer's disease (AD), Parkinson's disease (PD), attention deficit hyperactivity disorder (ADHD), autism, intellectual disability, and other developmental neurotoxicities. Apart from inhibiting the cholinesterase enzyme, OP compounds are believed to cause other pathological mechanisms at both the extracellular level (cholinergic, serotonergic, dopaminergic, glutamatergic, and GABAergic synapses) and the intracellular level (oxidative stress, mitochondrial dysfunction, inflammation, autophagy, and apoptosis) that contribute to these disorders. Specific genetic polymorphisms, including PON1, ABCB1, NOS, DRD4, GST, CYP, and APOE, have increased the risk of developing OP-related neurological disorders.

In Vitro Enzyme Kinetics and NMR-Based Product Elucidation for Glutathione S-Conjugation of the Anticancer Unsymmetrical Bisacridine C-2028 in Liver Microsomes and Cytosol: Major Role of Glutathione S-Transferase M1-1 Isoenzyme

This work is the next step in studying the interplay between C-2028 (anticancer-active unsymmetrical bisacridine developed in our group) and the glutathione S-transferase/glutathione (GST/GSH) system. Here, we analyzed the concentration- and pH-dependent GSH conjugation of C-2028 in rat liver microsomes and cytosol. We also applied three recombinant human GST isoenzymes, which altered expression was found in various tumors. The formation of GSH S-conjugate of C-2028 in liver subfractions followed Michaelis-Menten kinetics. We found that C-2028 was conjugated with GSH preferentially by GSTM1-1, revealing a sigmoidal kinetic model. Using a colorimetric assay (MTT test), we initially assessed the cellular GST/GSH-dependent biotransformation of C-2028 in relation to cytotoxicity against Du-145 human prostate cancer cells in the presence or absence of the modulator of GSH biosynthesis. Pretreatment of cells with buthionine sulfoximine resulted in a cytotoxicity decrease, suggesting a possible GSH-mediated bioactivation process. Altogether, our results confirmed the importance of GSH conjugation in C-2028 metabolism, which humans must consider when planning a treatment strategy. Finally, nuclear magnetic resonance spectroscopy elucidated the structure of the GSH-derived product of C-2028. Hence, synthesizing the compound standard necessary for further advanced biological and bioanalytical investigations will be achievable.

Association of Genetic and Allelic Variants of Von Willebrand Factor (VWF), Glutathione S-Transferase and Tumor Necrosis Factor Alpha with Ischemic Stroke Susceptibility and Progression in the Saudi Population

Stroke is a key cerebrovascular disease and important cause of death and disability worldwide, including in the kingdom of Saudi Arabia (KSA). It has a large economic burden and serious socioeconomic impacts on patients, their families and the community. The incidence of ischemic stroke is probably increased by the interaction of GSTT1 and GSTM1 null genotypes with high blood pressure, diabetes and cigarette smoking. The roles of VWF, GSTs and TNF-alpha gene variations in the induction of stroke are still uncertain and require further examination. In the current study, we studied the associations of SNPs in the genes VWF, GSTs and TNF-alpha with stroke in the Saudi population. Genotyping was performed using the ARMS -PCR for TNF-alpha, AS-PCR for VWF and multiplex PCR for GSTs. The study included 210 study subjects: 100 stroke cases and 110 healthy controls. We obtained significant distributions of VWF rs61748511 T > C, TNF-alpha rs1800629 G > A and GST rs4025935 and rs71748309 genotypes between stroke cases and the healthy controls (p < 0.05). The results also indicated that the TNF-alpha A allele was associated with risk of stroke with odd ratio (OR) = 2.22 and risk ratio = RR 2.47, p < 0.05. Similarly, the VWF-TC genotype and C allele were strongly linked with stroke with OR = 8.12 and RR 4.7, p < 0.05. In addition, GSTT1 and GSTT1 null genotype was strongly associated with stroke predisposition with OR = 8.30 and RR = 2.25, p < 0.0001. We conclude that there is a possible strong association between the VWF-T  > C, TNF-alpha G > A, GSTT1 gene variants and ischemic stroke susceptibility in the Saudi population. However, future well-designed and large-scale case-control studies on protein-protein interactions and protein functional studies are required to verify these findings and examine the effects of these SNPs on these proteins.

Genetic Polymorphisms in Oxidative Stress and Inflammatory Pathways as Potential Biomarkers in Alzheimer's Disease and Dementia

Oxidative stress and neuroinflammation are important processes involved in Alzheimer's disease (AD) and mild cognitive impairment (MCI). Numerous risk factors, including genetic background, can affect the complex interplay between those mechanisms in the aging brain and can also affect typical AD hallmarks: amyloid plaques and neurofibrillary tangles. Our aim was to evaluate the association of polymorphisms in oxidative stress- and inflammation-related genes with cerebrospinal fluid (CSF) biomarker levels and cognitive test results. The study included 54 AD patients, 14 MCI patients with pathological CSF biomarker levels, 20 MCI patients with normal CSF biomarker levels and 62 controls. Carriers of two polymorphic IL1B rs16944 alleles had higher CSF Aβ_1-42 levels (p = 0.025), while carriers of at least one polymorphic NFE2L2 rs35652124 allele had lower CSF Aβ_1-42 levels (p = 0.040). Association with IL1B rs16944 remained significant in the AD group (p = 0.029). Additionally, MIR146A rs2910164 was associated with Aβ_42/40 ratio (p = 0.043) in AD. Significant associations with cognitive test scores were observed for CAT rs1001179 (p = 0.022), GSTP1 rs1138272 (p = 0.005), KEAP1 rs1048290 and rs9676881 (both p = 0.019), as well as NFE2L2 rs35652124 (p = 0.030). In the AD group, IL1B rs1071676 (p = 0.004), KEAP1 rs1048290 and rs9676881 (both p = 0.035) remained associated with cognitive scores. Polymorphisms in antioxidative and inflammation genes might be associated with CSF biomarkers and cognitive test scores and could serve as additional biomarkers contributing to early diagnosis of dementia.

Glutathione in the nucleus accumbens regulates motivation to exert reward-incentivized effort

Emerging evidence is implicating mitochondrial function and metabolism in the nucleus accumbens in motivated performance. However, the brain is vulnerable to excessive oxidative insults resulting from neurometabolic processes, and whether antioxidant levels in the nucleus accumbens contribute to motivated performance is not known. Here, we identify a critical role for glutathione (GSH), the most important endogenous antioxidant in the brain, in motivation. Using proton magnetic resonance spectroscopy at ultra-high field in both male humans and rodent populations, we establish that higher accumbal GSH levels are highly predictive of better, and particularly, steady performance over time in effort-related tasks. Causality was established in in vivo experiments in rats that, first, showed that downregulating GSH levels through micro-injections of the GSH synthesis inhibitor buthionine sulfoximine in the nucleus accumbens impaired effort-based reward-incentivized performance. In addition, systemic treatment with the GSH precursor N-acetyl-cysteine increased accumbal GSH levels in rats and led to improved performance, potentially mediated by a cell-type-specific shift in glutamatergic inputs to accumbal medium spiny neurons. Our data indicate a close association between accumbal GSH levels and an individual’s capacity to exert reward-incentivized effort over time. They also suggest that improvement of accumbal antioxidant function may be a feasible approach to boost motivation.

Chemical interference with DSIF complex formation lowers synthesis of mutant huntingtin gene products and curtails mutant phenotypes

Earlier work has shown that siRNA-mediated reduction of the SUPT4H or SUPT5H proteins, which interact to form the DSIF complex and facilitate transcript elongation by RNA polymerase II (RNAPII), can decrease expression of mutant gene alleles containing nucleotide repeat expansions differentially. Using luminescence and fluorescence assays, we identified chemical compounds that interfere with the SUPT4H-SUPT5H interaction and then investigated their effects on synthesis of mRNA and protein encoded by mutant alleles containing repeat expansions in the huntingtin gene (HTT), which causes the inherited neurodegenerative disorder, Huntington's Disease (HD). Here we report that such chemical interference can differentially affect expression of HTT mutant alleles, and that a prototypical chemical, 6-azauridine (6-AZA), that targets the SUPT4H-SUPT5H interaction can modify the biological response to mutant HTT gene expression. Selective and dose-dependent effects of 6-AZA on expression of HTT alleles containing nucleotide repeat expansions were seen in multiple types of cells cultured in vitro, and in a Drosophila melanogaster animal model for HD. Lowering of mutant HD protein and mitigation of the Drosophila "rough eye" phenotype associated with degeneration of photoreceptor neurons in vivo were observed. Our findings indicate that chemical interference with DSIF complex formation can decrease biochemical and phenotypic effects of nucleotide repeat expansions.

Associations of Short-Term Exposure to Fine Particulate Matter with Neural Damage Biomarkers: A Panel Study of Healthy Retired Adults

Exposure to fine particulate matter (PM_2.5) is associated with various adverse health effects, such as respiratory and cardiovascular diseases. This study aimed to evaluate the association of PM_2.5 with neural damage biomarkers. A total of 34 healthy retirees were recruited from Xinxiang Medical University from December 2018 to April 2019. Concentrations of PM_2.5 constituents including 24 metals and nonmetallic elements and 6 ions, and 5 biomarkers of neural damage including brain-derived neurotrophic factor (BDNF), neurofilament light chain (NfL), neuron-specific enolase (NSE), protein gene product 9.5 (PGP9.5), and S100 calcium-binding protein B (S100B) in serum were measured. A linear mixed-effect model was employed to estimate the association of PM_2.5 and its constituents with neural damage biomarkers. Modification effects of glutathione S-transferase theta 1 gene (GSTT1) polymorphism, sex, education, and physical activity on PM_2.5 exposure with neural damage were explored. PM_2.5 and its key constituents were significantly associated with neural damage biomarkers. A 10 μg/m³ increase in PM_2.5 concentration was associated with 2.09% (95% CI, 39.3-76.5%), 100% (95% CI, 1.73-198%), and 122% (95% CI, 20.7-222%) increments in BDNF, NfL, and PGP9.5, respectively. Several constituents such as Cu, Zn, Ni, Mn, Sn, V, Rb, Pb, Al, Be, Cs, Co, Th, U, Cl^-, and F^- were significantly associated with NfL. The estimated association of PM_2.5 with NSE in GSTT1-sufficient volunteers was significantly higher than that in GSTT1-null volunteers. Therefore, short-term PM_2.5 exposure was associated with neural damage, and GSTT1 expression levels modified the PM_2.5-induced adverse neural effects.

50-bp insertion/deletion polymorphism of the superoxide dismutase-1 is associated with bladder cancer risk in an Iranian population

Bladder cancer (BC) is considered the sixth prevalent malignancy in men and the ninth leading cause of malignancy-related worldwide. Superoxide dismutase (SOD) is an antioxidant enzyme in the defense system against oxidative stress. Hence, we aimed to investigate whether the 50 bp Insertion/Deletion(Ins/Del) polymorphism of the SOD1 associated with the risk of BC. The study was conducted on 158 BC patients and 153 age-matched healthy subjects. Genomic DNA from all individuals was screened for the 50-bp SOD1 promoter deletion using PCR assay. Our results demonstrated an association between SOD1 Ins/Del (45% vs. 32%) genotype and risk of BC and this genotype elevated the susceptibility to BC (OR = 1.80, 95% CI: (1.10-2.90), P = 0.01). In addition, the Del allele of the SOD1 variation was detected to be more prevalent in the BC patients with the frequency of 28% and 20% in cases and healthy groups, correspondingly (OR = 1.61, 95% CI: (1.10-2.36), P = 0.01). It seems that SOD1 50-bp Ins/Del genotype, as well as Del, allele, is associated with an increased risk of BC in an Iranian population. However, further investigations in more diverse populations are necessary to assess the value of the novel biomarkers as a risk stratification biomarker for BC.

Glutathione S-Transferase Polymorphisms and Clinical Characteristics in Autism Spectrum Disorders

Background: Autism spectrum disorders (ASD) are a heterogeneous group of developmental disorders, with different levels of symptoms, functioning, and comorbidities. Recent findings suggested that oxidative stress and genetic variability in glutathione S-transferases (GSTs) might increase the risk of ASD development. We aimed to determine whether GST polymorphisms influence the severity of symptoms as well as the cognitive and adaptive abilities in children with ASD. Methods: The sample included 113 ASD cases. All participants were genotyped for GSTA1, GSTM1, GSTT1, and GSTP1 polymorphisms. The clinical characteristics were determined with Autism Diagnostic Interview-Revised (ADI-R) in all of the participants. In non-verbal participants, we explored the adaptive functioning using the Vineland Adaptive Behavior Scale II, while in verbal participants, we used the Wechsler Abbreviated Scale of Intelligence (WASI). Results: It was shown that the GSTA1 * CC genotype was a predictor of a lower non-verbal communication impairment as well as of a lower chance of having seizures during life. GSTM1-active genotype predicted a higher adaptive functioning. The predictive effect of GSTA1, GSTM1, and GSTT1 genotype was moderated by exposure during pregnancy (maternal smoking and medication). The GSTP1 * IleIle genotype was significantly associated to a better cognitive functioning in children with ASD. Conclusion: Besides the complex gene-environment interaction for the specific risk of developing ASD, there is also a possible complexity of interactions between genetic and environmental factors influencing the level of symptoms and impairment in people with ASD. Detoxification and antioxidant enzymes, such as GSTA1, might contribute to the core of this complexity.

[Deletion polymorphism of GSTT1 gene and lipid peroxidation hyperactivation in menopausal insomnia]

OBJECTIVE

A comparative analysis of the parameters of lipid peroxidation - antioxidant defense system in menopausal women with- and without insomnia, depending on the GSTT1 polymorphism.

MATERIAL AND METHODS

The study included 181 menopausal Caucasian women (ethnic group - Russians), who according to the results of the clinical-anamnestic examinations were divided into insomnia group (n=120, age 53.68±4.61 years, body mass index 26.47±3.73 kg/m²) and control group (n=61, age 52.64±4.91 years, body mass index 27.69±3.11 kg/m²). The insomnia group was formed according to the clinical guidelines for the diagnosis and treatment of chronic insomnia in adults, and scores of the Insomnia Severity Index. The study of the GSTT1 gene polymorphism was carried out using polymerase chain reaction. The lipid peroxidation - antioxidant system parameters were determined by spectrofluorophotometric methods.

RESULTS

In the insomnia group, carriers of the normal GSTT1 genotype had higher diene conjugates with lower glutathione peroxidase activity as compared to controls. When comparing groups of women with the deletion in GSTT1, an increase in the content of substrates and lipid peroxidation products was observed at all stages of lipid peroxidation, oxidized glutathione, glutathione S-transferase activity with a decrease in the content of reduced glutathione and retinol in the insomnia group as compared to controls. In the insomnia group, carriers of the deletion genotype had a higher content of ketodienes/conjugated trienes and active products of thiobarbituric acid, a lower content of retinol and α-tocopherol as compared to the patients with normal GSTT1 genotype. Conclusions. Insomnia in the menopausal women is accompanied with the intensification of lipid peroxidation only in the carriers of the GSTT1 deletion genotype.

Genetic predisposition to the development of congenital heart diseases: Role of xenobiotic biotransformation genes

Congenital heart diseases are one of the most common multi-factorial fetal abnormalities caused by a complex of endo- and exogenous factors. It is known that mutations in xenobiotic biotransformation genes can be associated with the pathogenesis of congenital heart diseases. In the presented research, 131 children with congenital heart diseases and 101 women having children with this pathology were included in the study group. In control group, 103 healthy children and their mothers were included. Single-nucleotide polymorphisms in the xenobiotic biotransformation genes CYP1A1 (rs1048943), CYP1A2 (rs762551), GSTP1 (rs6591256, rs1871042 and rs17593068) were detected by the real-time polymerase chain reaction. Gene-gene interactions were determined using the Multifactor Dimensionality Reduction method. We obtained no difference in the frequency of CYP1A1, CYP1A2 and GSTP1 between the study and control groups. At the same time, the genetic combinations GSTP1 (rs6591256)-GSTP1 (rs1871042) and GSTP1 (rs6591256)-GSTP1 (rs1871042)-CYP1A1 (rs1048943) in women; and GSTP1 (rs1793068)-GSTP1 (rs6591256)-GSTP1 (rs1871042)-CYP1A1 (rs1048943)-CYP1A2 (rs762551) in children contribute to the pathogenesis of congenital heart diseases.

Antidepressant Effect and Modulation of the Redox System Mediated by Tannic Acid on Lipopolysaccharide-Induced Depressive and Inflammatory Changes in Mice

Depression is an emotional disorder that causes mental and physical changes, and has limited pharmacotherapy. Tannic acid (TA) is a polyphenol with previously described antioxidant and neuroprotective properties. The aim of this study was to evaluate the effects of TA on lipopolysaccharide (LPS)-induced depressive-like behavior, as well as oxidative stress parameters and TNF-α levels in the brains of mice. Animals were pretreated once daily, with TA (30 or 60 mg/kg), fluoxetine (20 mg/kg) or vehicle for 7 days. On the 7th day, the animals received a single injection of LPS (830 μg/kg). After 24 h, open field, forced swimming, tail suspension, and splash tests were conducted. The endotoxin induced depressive-like behavior in these mice and this was attenuated by TA. In the cerebral cortex, hippocampus, and striatum, LPS increased lipid peroxidation and reactive oxygen species production, and this was also prevented by TA administration. TA treatment also prevented a decrease in catalase activity within the striatum. Further, LPS administration caused increased levels of TNF-α in all brain structures, and this was prevented in the cortex by TA treatment. In conclusion, TA shows many neuroprotective properties, with demonstrated antioxidant, anti-inflammatory and antidepressant effects in this animal model of acute depressive-like behavior. Therefore, this compound could provide an alternative therapeutic approach for the treatment of depression.

Antioxidant and detoxycative mechanisms in central nervous system

Since the brain contains a large amount of polyunsaturated fatty acids, consumes up to 20% of oxygen used by the whole body and exhibits low antioxidants activity, it seems to be especially vulnerable to oxidative stress. The most important antioxidant enzymes are superoxide dismutase (SOD), which catalyze the dismutation of superoxide anion to hydrogen peroxide, catalase (CAT), which converts toxic hydrogen peroxide to water and oxygen, and glutathione peroxidase (Se-GSHPx), which reduces hydrogen peroxide and organic peroxides with glutathione as the cofactor. Among other detoxifying enzymes, the most significant is glutathione transferase (GST), which shows detoksyvarious catalytic activities allowing for removal of xenobiotics, reducing organic peroxides and oxidized cell components. One of the most important brain nonenzymatic antioxidants is reduced glutathione (GSH), which (individually or in cooperation with peroxidases) participates in the reduction of free radicals, repair of oxidative damage and the regeneration of other antioxidants, such as ascorbate or tocopherol. Glutathione as a cosubstrate of glutathione transferase scavenges toxic electrophilic compounds. Although the etiology of the major neurodegenerative diseases are unknown, numerous data suggest that reactive oxygen species play an important role. Even a small change in the level of antioxidants can leads to the many disorders in the CNS.

Sensitivity of glutathione S-transferases to high doses of acrylamide in albino wistar rats: Affinity purification, biochemical characterization and expression analysis

The main objectives of this study were to purify the glutathione S-transfereses (GSTs) and assess the effect of high doses of acrylamide (ACR) on male albino Wistar rat liver, kidney, testis and bran GST activities, and expression analysis of GST. ACR (50 mg/300 ml) was ingested for 40 days (20 doses) in drinking water on alternative days, on 40 day post ingestion the control and treated tissues were collected for GST purification by affinity column and biochemical characterization of GSTs by substrate specificities, and GST expression by immuno dot blots. In the analysis of the purified GSTs, we observed that liver GSTs were resolved in to three bands known as Yc, Yb and Ya; kidney GSTs were resolved in to two bands known as Yc and Ya; testis and brain GSTs were resolved as four bands known as Yc, Yb, Yβ and Yδ on 12.5% sodium dodecyl sulfate polyacrylamide gel (SDS PAGE). In the analysis of biochemical characterization, we observed a significant decrease (p < 0.05) in the specific activities of liver GST isoforms with the substrates 1-chloro 2,4-dinitrobenzene (CDNB), bromosulfophthalein (BSP), p-nitrophenyl acetate (pNPA), p-nitrobenzyl chloride (pNBC) and cumene hydroperoxide (CHP), but showed no activity with ethacrynic acid (ECA) and significant decrease (p < 0.05) in the specific activities of kidney GST isoforms with the substrates CDNB, pNPA, pNBC and CHP, but showed no activity with BSP and ECA, and a significant decrease (p < 0.05) in the specific activities of testis and brain GST isoforms with the substrates CDNB, BSP, pNPA, pNBC, ECA and CHP. In the analysis of immuno dot blots, we observed a decreased expression of liver, kidney, testis and brain GSTs. Through the affinity purification and biochemical characterization, we observed a tissue specific distribution of GSTs that is liver GSTs possess Yc, Yb and Ya sub units known as alpha (α) and mu (μ) class GSTs; kidney GSTs possess Yc and Ya sub units known as (α) alpha class GST; testis and brain GSTs possess Yc, Yb, Yβ and Yδ sub units known as alpha (α), mu (μ) and pi (π) class GSTs. Purification studies, biochemical characterization and immuno dot blot analysis were revealed the GSTs were sensitive to high doses of ACR and the high level exposure to ACR cause the damage of detoxification function of GST due to decreased expression and hence lead to cellular dysfunction of vital organs.

In vivo biochemical evaluations of some β-lactam group antibiotics on glutathione reductase and glutathione S- transferase enzyme activities

OBJECTIVES

The aim of this study was to investigate whether some of the cephalosporin group antibiotics have inhibition effects on GR and GST enzymes with important functions in the metabolic pathway.

METHODS

In this study, some selected cephalosporin group antibiotics on GST and GR enzyme was carried out using 96 rats. 16 groups (16 × 6) were created from these rats, divided to another 4 groups (4 × 24). The resulting groups were named as sham groups, cefazolin groups, cefuroxime groups and cefoperazone groups, respectively. The antibiotics used were injected to cefazolin, cefuroxime and cefoperazone groups. The inhibition effects of the antibiotics were measured in the different time intervals (1st, 3th, 5th, 7th). The statistical investigation of the results was performed using the SPSS software program.

RESULTS

Results revealed the complex effects of the tested substances on GR and GST activity at different time intervals and in different tissues (p < 0.05). This indicated that the tested substances could be exposed to different interactions in vivo.

CONCLUSION

The tested antibiotics showed some significant inhibition effects on the GST and GR enzyme activity in some tissues of brain, eye and muscle. The interaction of enzyme - the drug is a key factor to highlight the toxicological mechanism. For this reason, the results obtained from in vivo experiments are crucial to explane the physiological properties of the enzymes.

Hippocampal transcriptome reveals novel targets of FASD pathogenesis

INTRODUCTION

Prenatal alcohol exposure can contribute to fetal alcohol spectrum disorders (FASD), characterized by a myriad of developmental impairments affecting behavior and cognition. Studies show that many of these functional impairments are associated with the hippocampus, a structure exhibiting exquisite vulnerability to developmental alcohol exposure and critically implicated in learning and memory; however, mechanisms underlying alcohol-induced hippocampal deficits remain poorly understood. By utilizing a high-throughput RNA-sequencing (RNA-seq) approach to address the neurobiological and molecular basis of prenatal alcohol-induced hippocampal functional deficits, we hypothesized that chronic binge prenatal alcohol exposure alters gene expression and global molecular pathways in the fetal hippocampus.

METHODS

Timed-pregnant Sprague-Dawley rats were randomly assigned to a pair-fed control (PF) or binge alcohol (ALC) treatment group on gestational day (GD) 4. ALC dams acclimatized from GDs 5-10 with a daily treatment of 4.5 g/kg alcohol and subsequently received 6 g/kg on GDs 11-20. PF dams received a once daily maltose dextrin gavage on GDs 5-20, isocalorically matching ALC counterparts. On GD 21, bilateral hippocampi were dissected, flash frozen, and stored at -80° C. Total RNA was then isolated from homogenized tissues. Samples were normalized to ~4nM and pooled equally. Sequencing was performed by Illumina NextSeq 500 on a 75 cycle, single-end sequencing run.

RESULTS

RNA-seq identified 13,388 genes, of these, 76 genes showed a significant difference (p < 0.05, log2 fold change ≥2) in expression between the PF and ALC groups. Forty-nine genes showed sex-dependent dysregulation; IPA analysis showed among female offspring, dysregulated pathways included proline and citrulline biosynthesis, whereas in males, xenobiotic metabolism signaling and alaninine biosynthesis etc. were altered.

CONCLUSION

We conclude that chronic binge alcohol exposure during pregnancy dysregulates fetal hippocampal gene expression in a sex-specific manner. Identification of subtle, transcriptome-level dysregulation in hippocampal molecular pathways offers potential mechanistic insights underlying FASD pathogenesis.