GABRA2 Research Articles

Early growth response 1 (Egr-1) directly regulates GABAA receptor α2, α4, and θ subunits in the hippocampus.

The homeostatic regulation of neuronal activity in glutamatergic and GABAergic synapses is critical for neural circuit development and synaptic plasticity. The induced expression of the transcription factor early growth response 1 (Egr-1) in neurons is tightly associated with many forms of neuronal activity, but the underlying target genes in the brain remained to be elucidated. This study uses a quantitative real-time PCR approach, in combination with invivo chromatin immunoprecipitation, and reveals that GABAA receptor subunit, GABRA2 (α2), GABRA4 (α4), and GABRQ (θ) genes, are transcriptional targets of Egr-1. Transfection of a construct that over-expresses Egr-1 in neuroblastoma (Neuro2A) cells up-regulates the α2, α4, and θ subunits. Given that Egr-1 knockout mice display less GABRA2, GABRA4, and GRBRQ mRNA in the hippocampus, and that Egr-1 directly binds to their promoters and induces mRNA expression, the present findings support a role for Egr-1 as a major regulator for altered GABAA receptor composition in homeostatic plasticity, in a glutamatergic activity-dependent manner. The early growth response 1 (Egr-1) is an inducible transcription factor to mediate rapid gene expression by neuronal activity. However, its underlying molecular target genes and mechanisms are not fully understood. We suggest that GABAA receptor subunits, GABRA2 (α2), GABRA4 (α4), and GABRQ (θ) genes are transcriptional targets of Egr-1. Neuronal activity-dependent up-regulation of Egr-1 might lead to altered subtypes of GABAA receptors for the maintenance of homeostatic excitatory and inhibitory balance for the regulation of synaptic strength.

Deletion of the Wolfram syndrome-related gene Wfs1 results in increased sensitivity to ethanol in female mice

Wolfram syndrome, induced by mutation in WFS1 gene, increases risk of developing mood disorders in humans. In mice, Wfs1 deficiency cause higher anxiety-like behaviour and increased response to anxiolytic-like effect of diazepam, a GABAA receptor agonist. As GABAergic system is also target for ethanol, we analysed its anxiolytic-like and sedative properties in Wfs1-deficient mice using elevated plus-maze test and tests measuring locomotor activity and coordination, respectively. Additionally loss of righting reflex test was conducted to study sedative/hypnotic properties of ethanol, ketamine and pentobarbital. To evaluate pharmacokinetics of ethanol in mice enzymatic colour test was used. Finally, gene expression of alpha subunits of GABAA receptors following ethanol treatment was studied by real-time-PCR. Compared to wild-types, Wfs1-deficient mice were more sensitive to ethanol-induced anxiolytic-like effect, but less responsive to impairment of motor coordination. Ethanol and pentobarbital, but not ketamine, caused longer duration of hypnosis in Wfs1-deficient mice. The expression of Gabra2 subunit at 30 minutes after ethanol injection was significantly increased in the frontal cortex of Wfs1-deficient mice as compared to respective vehicle-treated mice. For the temporal lobe, similar change in Gabra2 mRNA occurred at 60 minutes after ethanol treatment in Wfs1-deficient mice. No changes were detected in Gabra1 and Gabra3 mRNA following ethanol treatment. Taken together, increased anxiolytic-like effect of ethanol in Wfs1-deficient mice is probably related to altered Gabra2 gene expression. Increased anti-anxiety effect of GABAA receptor agonists in the present work and earlier studies (Luuk et al., 2009) further suggests importance of Wfs1 gene in the regulation of emotional behaviour.

Association study of GABAA α2 receptor subunit gene variants in antipsychotic-associated weight gain.

Schizophrenia treatment has been hampered by undesirable adverse effects, including weight gain and associated complications. Recent candidate gene studies have been exploring the appetite regulation pathways in antipsychotic-associated weight gain (AAWG) with some promising leads. Genome-wide association studies of obesity have pointed to a number of potential candidate genes, such as MC4R, that were later found to be shared with AAWG. GABAA α2 receptor subunit (GABRA2) was another potential candidate gene for obesity from genome-wide association studies; however, it has not been explored in AAWG. We examined 9 single nucleotide polymorphisms across the GABRA2 gene. Prospective weight change was assessed for a total of 160 schizophrenia patients of European ancestry. The rs279858 marker was associated with percent weight change, with the patients homozygous for the TT genotype experiencing higher percentage weight gain on average than the C allele carriers (P = 0.009). When we performed the analysis considering each clinical site using a meta-analytic method, the results remained statistically significant (P = 1.4e-4). These findings became even more significant when we considered only patients taking clozapine or olanzapine, the 2 medications with higher risk for weight gain (P < 1e-10). GABRA2 genetic variants may play a role in predicting AAWG. However, replication in larger and independent samples is required.

Heritability and molecular-genetic basis of resting EEG activity: a genome-wide association study.

Several EEG parameters are potential endophenotypes for different psychiatric disorders. The present study consists of a comprehensive behavioral- and molecular-genetic analysis of such parameters in a large community sample (N = 4,026) of adolescent twins and their parents, genotyped for 527,829 single nucleotide polymorphisms (SNPs). Biometric heritability estimates ranged from .49 to .85, with a median of .78. The additive effect of all SNPs (SNP heritability) varied across electrodes. Although individual SNPs were not significantly associated with EEG parameters, several genes were associated with delta power. We also obtained an association between the GABRA2 gene and beta power (p < .014), consistent with findings reported by others, although this did not survive Bonferroni correction. If EEG parameters conform to a largely polygenic model of inheritance, larger sample sizes will be required to detect individual variants reliably.

Single-cell genetic expression of mutant GABAA receptors causing Human genetic epilepsy alters dendritic spine and GABAergic bouton formation in a mutation-specific manner.

Mutations in genes encoding for GABAA receptor subunits is a well-established cause of genetic generalized epilepsy. GABA neurotransmission is implicated in several developmental processes including neurite outgrowth and synapse formation. Alteration in excitatory/inhibitory synaptic activities plays a critical role in epilepsy, thus here we investigated whether mutations in α1 subunit of GABAA receptor may affect dendritic spine and GABAergic bouton formation. In particular, we examined the effects of three mutations of the GABRA1 gene (D219N, A322D and K353delins18X) that were found in a cohort of French Canadian families with genetic generalized epilepsy. We used a novel single-cell genetic approach, by preparing cortical organotypic cultures from GABRA1flox/flox mice and simultaneously inactivating endogenous GABRA1 and transfecting mutant α1 subunits in single glutamatergic pyramidal cells and basket GABAergic interneurons by biolistic transfection. We found that GABRA1−/− GABAergic cells showed reduced innervation field, which was rescued by co-expressing α1-A322D and α1-WT but not α1-D219N. We further found that the expression of the most severe GABRA1 missense mutation (α1-A322D) induced a striking increase of spine density in pyramidal cells along with an increase in the number of mushroom-like spines. In addition, α1-A322D expression in GABAergic cells slightly increased perisomatic bouton density, whereas other mutations did not alter bouton formation. All together, these results suggest that the effects of different GABAAR mutations on GABAergic bouton and dendritic spine formation are specific to the mutation and cannot be always explained by a simple loss-of-function gene model. The use of single cell genetic manipulation in organotypic cultures may provide a better understanding of the specific and distinct neural circuit alterations caused by different GABAA receptor subunit mutations and will help define the pathophysiology of genetic generalized epilepsy syndromes.

'Idiopathic' no more! Abnormal interaction of large-scale brain networks in generalized epilepsy.

This scientific commentary refers to ‘Motor co-activation in siblings of patients with juvenile myoclonic epilepsy: an imaging endophenotype?’, by Wandschneider et al. (doi: 10.1093/brain/awu175). In this issue of Brain , Wandschneider and colleagues (2014) report that relatives of patients with juvenile myoclonic epilepsy (JME) show changes in functional MRI, indicating altered motor system activation and functional connectivity, similar to those seen in patients themselves (Vollmar et al. , 2011). This study reflects the maturation of the field of imaging, particularly the use of advanced functional MRI analysis. Why is this of interest? We see two major potential contributions of these data; first, the concept of an imaging endophenotype and its specificity and, second, further understanding of the fundamental disease mechanism. Juvenile myoclonic epilepsy is an important epilepsy syndrome because it is common and easily treatable, yet often misdiagnosed. It belongs to the family of generalized epilepsies, formally designated as ‘idiopathic’ or ‘primary’, but now referred to as genetic generalized epilepsies because of the strong evidence of genetic aetiology (Berg et al. , 2010), although the specific genetic determinants remain largely elusive. A few very rare families segregate an autosomal dominant gene, the best documented cases being mutations in the GABRA1 gene, which encodes a GABA receptor subunit. Clinical genetic evidence derived from family studies and twin analyses strongly supports the contention that juvenile myoclonic epilepsy is a complex disorder with multiple genetic components (see Helbig et al. , 2008 and references therein). Deep sequencing has …

Research Highlights: highlights from the latest articles focusing on a new gene set for better drug response prediction of epilepsy patients.

PharmacogenomicsVol. 15, No. 5 News & ViewsResearch Highlights: Highlights from the latest articles focusing on a new gene set for better drug response prediction of epilepsy patientsRuchi Baghel , Ajay Jajodia , Sandeep Grover & Ritushree KukretiRuchi BaghelGenomics & Molecular Medicine Unit, Institute of Genomics & Integrative Biology (IGIB), Council of Scientific & Industrial Research (CSIR), Mall Road, Delhi 110 007, IndiaSearch for more papers by this author , Ajay JajodiaGenomics & Molecular Medicine Unit, Institute of Genomics & Integrative Biology (IGIB), Council of Scientific & Industrial Research (CSIR), Mall Road, Delhi 110 007, IndiaSearch for more papers by this author , Sandeep GroverGenomics & Molecular Medicine Unit, Institute of Genomics & Integrative Biology (IGIB), Council of Scientific & Industrial Research (CSIR), Mall Road, Delhi 110 007, IndiaSearch for more papers by this author & Ritushree Kukreti* Author for correspondence: E-mail Address: ritus@igib.res.inGenomics & Molecular Medicine Unit, Institute of Genomics & Integrative Biology (IGIB), Council of Scientific & Industrial Research (CSIR), Mall Road, Delhi 110 007, IndiaSearch for more papers by this authorPublished Online:5 May 2014https://doi.org/10.2217/pgs.14.11AboutSectionsView ArticleView Full TextPDF/EPUB ToolsAdd to favoritesDownload CitationsTrack CitationsPermissionsReprints ShareShare onFacebookTwitterLinkedInRedditEmail View articleFiguresReferencesRelatedDetailsCited ByDysfunction of the SNARE complex in neurological and psychiatric disordersPharmacological Research, Vol. 165Integration of epigenomics and metabolomics: From biomarkers discovery to personalized medicineEvaluating the Role of Genetic Variants on first-line antiepileptic drug response in North India: Significance of SCN1A and GABRA1 Gene Variants in Phenytoin Monotherapy and its Serum Drug Levels1 June 2016 | CNS Neuroscience & Therapeutics, Vol. 22, No. 9Synergistic association of STX 1A and VAMP 2 with cryptogenic epilepsy in North Indian population14 June 2016 | Brain and Behavior, Vol. 6, No. 7 Vol. 15, No. 5 Follow us on social media for the latest updates Metrics Downloaded 92 times History Published online 5 May 2014 Published in print April 2014 Information© Future Medicine LtdPDF download

EPA-1077 – Haplotype analysis of GABRA2 gene polymorphisms in alcohol dependence

Introduction Studies aimed at the identification of potential risk factors of the alcohol dependence syndrome (ADS) and, consequently, of risk groups of this condition that should be subjected to preventive programs, are being undertaken since many years. The aims of this study were (1) to analyze the effects of polymorphisms in the GABRA2 gene on the risk of alcoholism; (2) to determine associations between some genetic markers basing on haplotype analysis; Material and methods The study included 305 Caucasian males, among them 156 patients with ADS and 149 controls. These two groups, were compared as to the frequencies of haplotypes of the following polymorphisms: rs 279826, rs 279871, 279845 of the GABRA2 gene. All subjects were recruited in the North West region of Poland. Alcohol use and family history of alcoholism were assessed by means of a structured interview, based on the Polish version of Semi-Structured Assessment on Genetics in Alcoholism (SSAGA). Genomic DNA was extracted from venous blood. Polymorphisms were detected using PCR real time method. Conclusions Significant relationships documented by the haplotype analysis of ADS patients point to the usefulness of haplotype constructions in etiopathogenetic studies of ADS. The protective haplotype was G-G-A (p=0,01). In conclusion, larger – possibly multicentre – studies are needed to finally uncover the role of GABRA2 gene in determining ADS. Moreover, other candidate genes with a possible impact on the phenotype of alcohol-dependent individuals should be sought. Supported by grant of Ministry of Science and Higher Education (MNiSW no.: NN 402466540 ).

EPA-1081 - Case - control study of GABRA2 gene polymorphisms in alcohol dependence

Introduction Alcohol dependence (AD) is a highly prevalent disorder that is associated with serious morbidity and mortality. The development of alcohol dependence is the result of an interaction between environmental and hereditary factors. Previous studies have implicated GABRA2 receptor genes with AD, alcohol use patterns, and levels of response to alcohol. The aims of this study were to analyze the effects of polymorphisms in the GABRA2 gene on the risk of alcoholism ; associations between genotypes and alleles were studied; Material and methods This study included a group of 161 Caucasian subjects, with no history of psychiatric disorders other than alcohol or nicotine dependence as classified by ICD-10. The control group comprised 150 unrelated individuals matched for ethnicity and gender, and excluded for mental disorders using the Primary Care Evaluation of Mental Disorders questionnaire. All subjects were recruited in the North West region of Poland. Alcohol use and family history of alcoholism were assessed by means of a structured interview, based on the Polish version of Semi-Structured Assessment on Genetics in Alcoholism (SSAGA). Genomic DNA was extracted from venous blood. Polymorphisms (rs 279826, rs 279871, rs279845) were detected using PCR real time method. Conclusions Significant associations for genotypes and alleles were observed in rs 279871 polymorphism (p=0,31). The advantage of this research is that the genetic analysis of GABRA2 gene rs 279871 polymorphism was conducted on quite large and, most importantly, homogenous subgroups of alcohol-dependent patients. Supported by grant of Ministry of Science and Higher Education (MNiSW no.: NN 402466540 ).

Interaction between γ-Aminobutyric Acid A Receptor Genes: New Evidence in Migraine Susceptibility

Migraine is a common neurological episodic disorder with a female-to-male prevalence 3- to 4-fold higher, suggesting a possible X-linked genetic component. Our aims were to assess the role of common variants of gamma-aminobutyric acid A receptor (GABAAR) genes, located in the X-chromosome, in migraine susceptibility and the possible interaction between them. An association study with 188 unrelated cases and 286 migraine-free controls age- and ethnic matched was performed. Twenty-three tagging SNPs were selected in three genes (GABRE, GABRA3 and GABRQ). Allelic, genotypic and haplotypic frequencies were compared between cases and controls. We also focused on gene-gene interactions. The AT genotype of rs3810651 of GABRQ gene was associated with an increased risk for migraine (OR: 4.07; 95% CI: 1.71-9.73, p=0.002), while the CT genotype of rs3902802 (OR: 0.41; 95% CI: 0.21-0.78, p=0.006) and GA genotype of rs2131190 of GABRA3 gene (OR: 0.53; 95% CI: 0.32-0.88, p=0.013) seem to be protective factors. All associations were found in the female group and maintained significance after Bonferroni correction. We also found three nominal associations in the allelic analyses although there were no significant results in the haplotypic analyses. Strikingly, we found strong interactions between six SNPs encoding for different subunits of GABAAR, all significant after permutation correction. To our knowledge, we show for the first time, the putative involvement of polymorphisms in GABAAR genes in migraine susceptibility and more importantly we unraveled a role for novel gene-gene interactions opening new perspectives for the development of more effective treatments.

Expression of gamma-aminobutyric acid receptors on neoplastic growth and prediction of prognosis in non-small cell lung cancer

BackgroundGamma-aminobutyric acid (GABA) is the main inhibitory neurotransmitter in the adult mammalian brain, but exerts physiologic effects other than that on neurotransmitter in non-neuronal peripheral tissues and organs. GABA may affect cancer growth through activation GABA receptors. We investigated the gene expression of GABA receptors in tissue of non-small cell lung cancers (NSCLC) and non-cancerous tissues, and found that the gene expression of GABA receptor phenotypes was correlated with tumorigenesis and clinical prognosis.MethodsSixty-one snap-frozen human samples of NSCLC tissues and paired non-cancerous tissues (5cm away from tumor) were analyzed. Gene expression of GABA receptors was detected by Real-time quantitative PCR (RT-qPCR). Survival times in relation to the expression of GABA receptor phenotypes were analyzed. Human NSCLC cell lines H1299, A549, H520, H460 and human bronchial epithelial cell line BEAS-2B were used to determine the phenotypes of GABA inhibitory effects on cancer cell growth. The effects of exogenous administration of GABA on H1299 cell growth were examined.ResultsThe gene expressions were significantly higher in NSCLC tissues than in the paired non-cancerous tissues for GABAA receptor subunit α3 (GABRA3, P = 0.030); for GABAA receptor subunit epsilon (GABRE, P = 0.036); and GABAB receptor subunit 2 (GABBR2, P = 0.005). Kaplan-Meier curves showed that patients with high expression of GABBR2 gene and low expression of GABRA3 gene had a better prognosis (P < 0.05). The administration of GABA resulted in suppressed proliferation of NSCLC cell lines in a dose- and time-dependent manner. The use of the GABA receptor antagonist CGP35348 could reverse the inhibitory effect.ConclusionsThe pattern of GABA receptor gene phenotype expression may be involved in the regulation of tumorigenesis. A high expression of GABBR2 with a low expression of GABRA3 may predict a better outcome. The treatment with GABA attenuates cancer cell growth in vitro. The expression of GABA receptor may be not only promising genetic therapeutic targets but may also serve as valuable prognostic markers for NSCLC.

Genetic Moderation of the Impact of Parenting on Hostility Toward Romantic Partners

Although GxE studies are typically based on the assumption that some individuals possess genetic variants that enhance their vulnerability to environmental adversity, the differential susceptibility model posits that these individuals are simply more sensitive to social context, whether that context be adverse or supportive. Thus those persons most vulnerable to adversity are the same ones who reap the most benefit from support. This idea was tested using longitudinal data from a sample of several hundred African Americans. Findings indicated that relatively common variants of the GABRA2 gene interact with parenting to predict hostility toward romantic partners in a manner consonant with the differential susceptibility hypothesis. Individuals with these genetic variants displayed more aggression toward their partner than those with other genotypes when they had been subjected to harsh parenting, but exhibited less aggression toward their partner than other genotypes if their parents avoided harsh parenting practices.

Deletion of the gabra2 Gene Results in Hypersensitivity to the Acute Effects of Ethanol but Does Not Alter Ethanol Self Administration

Human genetic studies have suggested that polymorphisms of the GABRA2 gene encoding the GABAA α2-subunit are associated with ethanol dependence. Variations in this gene also convey sensitivity to the subjective effects of ethanol, indicating a role in mediating ethanol-related behaviours. We therefore investigated the consequences of deleting the α2-subunit on the ataxic and rewarding properties of ethanol in mice. Ataxic and sedative effects of ethanol were explored in GABAA α2-subunit wildtype (WT) and knockout (KO) mice using a Rotarod apparatus, wire hang and the duration of loss of righting reflex. Following training, KO mice showed shorter latencies to fall than WT littermates under ethanol (2 g/kg i.p.) in both Rotarod and wire hang tests. After administration of ethanol (3.5 g/kg i.p.), KO mice took longer to regain the righting reflex than WT mice. To ensure the acute effects are not due to the gabra2 deletion affecting pharmacokinetics, blood ethanol concentrations were measured at 20 minute intervals after acute administration (2 g/kg i.p.), and did not differ between genotypes. To investigate ethanol’s rewarding properties, WT and KO mice were trained to lever press to receive increasing concentrations of ethanol on an FR4 schedule of reinforcement. Both WT and KO mice self-administered ethanol at similar rates, with no differences in the numbers of reinforcers earned. These data indicate a protective role for α2-subunits, against the acute sedative and ataxic effects of ethanol. However, no change was observed in ethanol self administration, suggesting the rewarding effects of ethanol remain unchanged.

Characterization of CpG island DNA methylation of impairment-related genes in a rat model of cognitive aging

Cognitive abilities, particularly memory formation, vary substantially in the elderly, with some individuals exhibiting dramatic decline with age while others maintain function well into late life. Epigenetic modifications suggest an intriguing mechanism to account for the range of cognitive outcomes in aging as they are responsive to environmental influences and affect gene transcription in cognitively relevant brain regions. Leveraging a well-characterized rat model of neurocognitive aging that recapitulates the range of outcomes seen in humans, we previously identified gene expression profiles in the CA3 subregion of the hippocampus that distinguish between young and aged subjects as well as between impaired and preserved spatial memory function. To investigate the influence of epigenetics on these profiles, we examined genomic CpG DNA methylation in the promoter regions of three neurophysiologically relevant genes (Gabra5, Hspa5 and Syn1) whose expression levels decrease with age and correlate with spatial memory performance. Consistent with mRNA decreases, DNA methylation increased in aged rats relative to young in CpG dense regions of all target promoters examined. However, no correlation with cognition was found. Focused analysis of the Gabra5 gene found that methylation changes were limited to the CpG island and varied substantially across individual CpGs. Methylation at one CpG correlated with learning and demonstrated a significant difference between memory impaired aged rats and those with intact learning. These data provide evidence that broad age-dependent DNA methylation changes occur in CpG dense promoter regions of cognitively relevant genes but suggest that methylation at single CpGs may be more pertinent to individual cognitive differences.

The GABAAreceptor α2 subunit gene (GABRA2) is associated with alcohol-related behavior

Background Gamma-aminobutyric acid-A (GABA-A) receptors, the major inhibitory neurotransmitter receptors in the brain are implicated in the acute and chronic effects of alcohol, including tolerance, dependence and withdrawal. Various polymorphisms in the gene encoding the GABA-A receptor alpha2 subunit (GABRA2) have been associated with alcoholism and with antisocial behavior in different populations of European ancestry. As early onset of alcoholism often reflects greater severity, including a higher risk for recurrence, comorbid antisocial personality disorder and conduct disorder, Cloninger’s classification distinguishes type II alcoholism with an early onset, elevated levels of antisocial behavior and delinquency, from the type I alcoholism with a late onset, neurotic symptoms and minimal criminality. Materials and methods Genotyping of GABRA2 polymorphisms (rs567926, rs279858 and rs9291283) was performed in samples of 355 alcoholic patients of Croatian origin (280 males and 75 females) using TaqMan Real-Time allelic discrimination technique after extraction of DNA from the whole blood. The results of allelic and haplotypic analysis were compared between alcohol-dependent subjects with a combination of early onset of alcohol abuse and presence of aggressive behavior corresponding to type II alcoholism subgroup, and individuals with the late onset of alcohol abuse and without aggression corresponding to type I alcoholism subgroup, according to Cloninger. Results Cloninger’s Type I and Type II alcohol-dependent patients did not differ significantly in the frequency of the genotypes and alleles for rs567926, rs279858 or rs9291283. However, the G-T- G haplotype was more often present in the alcohol- dependent subjects with early onset of alcohol abuse and aggressive behavior, corresponding to the Cloninger type II alcoholism subgroup (χ2 = 6.102, p = 0.013). Conclusions Our results revealed a haplotypic association between the GABRA2 gene and a more severe form of alcoholism, characterized by the early onset of alcohol abuse and presence of aggressive behavior. These findings support an important role of GABA-A receptors in the susceptibility to alcoholism and highlight them as potential targets for novel therapeutics in the treatment of alcohol dependence.

Voluntary intravenous self-administration of alcohol detects an interaction between GABAergic manipulation and GABRG1 polymorphism genotype: a pilot study.

Operant responding paradigms quantify a subject's motivation for reward, but such studies employing ingested alcohol cannot assure the same incremental increase in brain exposure to alcohol across subjects because of substantial variability in absorption kinetics. We developed a human progressive ratio (PR) paradigm using the computer-assisted self-infusion of ethanol (CASE) system that overcomes such variability and conducted a pilot study to assess its utility for detecting an interaction of subjects' GABRA2 or GABRG1 genotype and pretreatment with 1 mg of lorazepam (LZ) vs. placebo on their willingness to work for alcohol rewards. Twenty healthy, nondependent drinkers, aged 21 to 27, were balanced on rs279871 and rs2350439 single nucleotide polymorphisms in the GABRA2 and GABRG1 genes, respectively. Subjects worked for alcohol, with water as an alternative reinforcer (AR), using a progressive schedule of a task that required constant attention and adapted to both fatigue and drug effects. Testing began 1 hour after pretreatment with 1 mg LZ or placebo in a crossover design. The CASE system performed well, and the constant attention task was perceived as work by all subjects. GABRA2 homozygosity did not significantly predict either breakpoint or cumulative work, whereas a significant GABRG1 genotype by LZ pretreatment interaction for cumulative work was detected (p = 0.04). Breakpoint revealed a weak trend toward pretreatment drug effects (p = 0.11), and a somewhat stronger interaction of LZ pretreatment with GABRG1 genotype (p = 0.06). GABRG1 status revealed a more complex relationship with respect to motivation for alcohol with and without LZ pretreatment; AG and GG individuals worked more for alcohol under both pretreatment conditions, while AA individuals worked more for the AR. The CASE PR paradigm shows promise as a laboratory method for use in drug development and phenotyping studies.

Gabra5-gene haplotype block associated with behavioral properties of the full agonist benzodiazepine chlordiazepoxide

The gabra5 gene is associated with pharmacological properties (myorelaxant, amnesic, anxiolytic) of benzodiazepines. It is tightly located (0.5cM) close to the pink-eyed dilution (p) locus which encodes for fur color on mouse chromosome 7. We tested the putative role of the gabra5 gene in pharmacological properties of the full non specific agonist chlordiazepoxide (CDP), using behavioral and molecular approaches in mutated p/p mice and wild type F2 from crosses between two multiple markers inbred strain ABP/Le and C57BL/6By strain. From our results, using rotarod, light–dark box, elevated maze and radial arm maze tests, we demonstrate that p/p mice are more sensitive than WT to the sensory motor, anxiolytic and amnesic effect of CDP. This is associated with the presence of a haplotypic block on the murine chromosome 7 and with an up regulation of gabra5 mRNAs in hippocampi of p/p F2 mice.

Effects of SCN1A and GABA Receptor Genetic Polymorphisms on Carbamazepine Tolerability and Efficacy in Chinese Patients with Partial Seizures: 2‐Year Longitudinal Clinical Follow‐Up

To investigate the tolerability and efficacy of carbamazepine treatment in patients with partial-onset seizures and the association with polymorphisms in the sodium channel α-subunit type 1 (SCN1A), and gamma-aminobutyric acid (GABA) receptor genes among the Chinese Han population. 448 patients were genotyped for single nucleotide polymorphisms selected of the SCN1A and GABA-receptor genes. Monotherapy with carbamazepine (CBZ) was administered to the patients. The effectiveness of CBZ treatment was evaluated with regard to efficacy by the decrease in seizures and tolerability by retention rates. SCN1A rs3812718 A/G with CBZ tolerability (P= 0.038) throughout 24 months of clinical follow-up and the GABRA1 rs2290732 A/G were significantly associated with CBZ tolerability (P= 0.001). The maintenance dose and serum level of CBZ in AA genotype carriers of rs3812718 A/G were significantly higher than those of GG genotype carriers between 3 and 12 months of follow-up. The proportion of AA genotype carriers of rs2298771 A/G with seizure free was significantly higher than that of AG+GG genotype carriers from 3 months to 15 months of follow-up (P < 0.05). rs3812718 A/G and rs2290732 A/G polymorphisms affected the tolerability of CBZ. rs2298771 A/G was associated with efficacy of CBZ treatment.

GABA-A receptor genes do not play a role in genetics of Lesch’s typology in Caucasian subjects

IntroductionLesch's typology differentiates alcoholics into different treatment response subgroups. The effects of ethanol are mediated, to an important extent, via the GABA-ergic system.Material and methodsWe have evaluated the linkage disequilibrium patterns and haplotype frequencies of GABRG1 and GABRA2 genes in 133 alcoholics divided according to Lesch's typology and in 145 matched controls.ResultsBesides several relationships at a threshold of statistical significance, we found no significant differences in the haplotype distribution of these genes between alcoholics and controls.ConclusionsLesch's typology may not be related with the genotype of alcoholics – at least in terms of genes with an established role in the development of dependency.

Mapping GABAA Receptor Single Nucleotide Polymorphisms (SNPs) Linked to Epilepsy: Insights into the Receptor Gating and Assembly

Missense polymorphisms or variants that affect function and/or expression of GABAA receptors (GABARs) have been associated with idiopathic generalized epilepsies (IGEs) in GABRA1, GABRA6, GABRB3, GABRG2 and GABRD genes. Three separate IGE-associated mutations were identified in GABAR subunits (β3(G32R), α6(Q237R) and γ2(K328M)), which represent a large range of GABARs in the nervous system. We sought to investigate the contributions of these mutations into the assembly and function of GABARs. Homology modeling suggested that G32R is located within the N-terminal α-helix β3 subunit domain, and Q237R and K328M are located within the pre-M1 segment of the N-terminal α6 subunit domain and the M2-M3 loop of the N-terminal γ2 subunit domain, respectively. We studied gating properties and surface expression of wild type (wt) α1β3γ2, α6β2γ2, α1β2γ2 and mutant α1β3(G32R)γ2, α6(Q237R)β2γ2, α1β2γ2(K328M) receptors expressed in HEK293T cells. We found that the mutations share common gating defects, but distinctive trafficking defects. Thus, mutant β3(G32R) subunits displayed a mixed profile, causing both gating and trafficking defects of α1β3γ2 receptors, whereas mutant α6(Q237R) and γ2(K328M) subunits caused exclusive channel gating defects of α6β2γ2 and α1β2γ2 receptors. Unexpected, homology modeling predicted that the β3(G32R) mutation affects a salt bridge across the γ2/β3 subunit interface, which underlies an assembly motif reported to be essential for inter-subunit interactions in assembled receptors. In contrast, α6(Q237R) and γ2(K328M) subunit mutations are predicted to interact with residues in Pre-M1 domain, M2-M3 loop and Cys-loop of α6 and γ2 subunits that are critical for desensitization-deactivation coupling of GABARs.NIH funding NS33300 to RLM.