Project description:Impulsivity and hyperactivity share common ground with numerous mental disorders, including schizophrenia. Recently, a population-specific serotonin 2B (5-HT2B) receptor stop codon (ie, HTR2B Q20*) was reported to segregate with severely impulsive individuals, whereas 5-HT2B mutant (Htr2B(-/-)) mice also showed high impulsivity. Interestingly, in the same cohort, early-onset schizophrenia was more prevalent in HTR2B Q*20 carriers. However, the putative role of 5-HT2B receptor in the neurobiology of schizophrenia has never been investigated. We assessed the effects of the genetic and the pharmacological ablation of 5-HT2B receptors in mice subjected to a comprehensive series of behavioral test screenings for schizophrenic-like symptoms and investigated relevant dopaminergic and glutamatergic neurochemical alterations in the cortex and the striatum. Domains related to the positive, negative, and cognitive symptom clusters of schizophrenia were affected in Htr2B(-/-) mice, as shown by deficits in sensorimotor gating, in selective attention, in social interactions, and in learning and memory processes. In addition, Htr2B(-/-) mice presented with enhanced locomotor response to the psychostimulants dizocilpine and amphetamine, and with robust alterations in sleep architecture. Moreover, ablation of 5-HT2B receptors induced a region-selective decrease of dopamine and glutamate concentrations in the dorsal striatum. Importantly, selected schizophrenic-like phenotypes and endophenotypes were rescued by chronic haloperidol treatment. We report herein that 5-HT2B receptor deficiency confers a wide spectrum of antipsychotic-sensitive schizophrenic-like behavioral and psychopharmacological phenotypes in mice and provide first evidence for a role of 5-HT2B receptors in the neurobiology of psychotic disorders.
Project description:There is conflicting evidence for the association between genetic polymorphisms in the serotonin (5-HT)2C receptor (HTR2C) and response to antipsychotic drugs (APD) in schizophrenic patients. We tested the association between the HTR2C polymorphisms, Cys23Ser, -759C/T, and -697G/C, and response to APDs (mainly clozapine) in a 6 month prospective study in 171 patients with schizophrenia. Ser23 was significantly associated with treatment response (positive symptoms, X 2 = 7.540, p = 0.01; negative symptoms, X 2 = 4.796, p = 0.03) in male patients only. A -759C-Ser23 haplotype was similar associated with positive (X 2 = 6.648, p = 0.01) and negative (X 2 = 6.702, p = 0.01) symptom improvement. Logistic regression, after controlling for covariates, also showed significant haplotypic associations. A meta-analysis of six studies for Ser23 and treatment response showed an overall odds ratio of 2.00 (95%CI, 1.38-2.91, p = 0.0003) or 1.94 (95%CI, 1.27-2.99, p = 0.0024) under fixed or random effect models. These results provide additional evidence that HTR2C polymorphisms are associated with treatment response to APD with HTR2C antagonism or inverse agonism, in male schizophrenic patients.
Project description:ObjectiveSchizophrenia is a severe highly heritable mental disorder. Genetic polymorphisms of dopaminergic pathways are related to pathogenesis of drug response. Hyperprolactinemia (HPRL), a common adverse effect of antipsychotics, is attributed to blockade of dopamine D2 receptors. Ankyrin Repeat and Kinase Domain containing 1 (ANKK1) gene is closely related to Dopamine Receptor D2 type (DRD2) gene functioning. We examined whether the functional polymorphism rs2734849 in the ANKK1 gene is associated with antipsychotic-induced HPRL.MethodsWe recruited 446 patients with schizophrenia from among the Russian population of the Siberian region. The polymorphism rs2734849 in the ANKK1 gene was genotyped with The MassARRAY® Analyzer 4 by Agena Bioscience™, using the kit SEQUENOM Consumables iPLEXGold 384. Genotype and allele frequencies were compared between groups of schizophrenia patients with and without HPRL using the χ2 test.ResultsA comparison between schizophrenia patients with and without HPRL revealed significantly higher frequency of the C allele of the polymorphic variant rs2734849 in the ANKK1 gene in patients with HPRL as compared to the patients without it (χ2 = 3.70; p = .05; odds ratio [OR] = 1.30 [0.99-1.69]).ConclusionThe functional polymorphism rs2734849 in the ANKK1 gene was associated with HPRL in patients with schizophrenia.
Project description:PurposeDyslipidemia frequently occurs in schizophrenia patients treated with antipsychotic drugs (APDs), especially atypical APDs. Apolipoprotein A1 (ApoA1) plays a key role in lipid metabolism. The aim of this study was to investigate whether ApoA1 gene polymorphisms are associated with APD-induced dyslipidemia in schizophrenia patients.Patients and methodsA total of 1987 patients with schizophrenia were enrolled in this study. Serum lipid profiles were determined with a biochemistry analyzer. Genotyping for the rs5072 polymorphism of ApoA1 was performed with TaqMan assay. Logistic regression analysis was carried out to evaluate the relationship between ApoA1 gene polymorphisms and APD-induced dyslipidemia. The effects of drug classification (typical vs atypical APD) and drug regimen (monotherapy vs combination therapy) on serum lipid levels were also analyzed.ResultsA significant association was found between rs5072 and triglyceride (TG) levels in the recessive model of the logistic regression analysis (adjusted odds ratio [OR]=1.50, 95% confidence interval [CI]: 1.03, 2.17; P<0.05). TG level was significantly higher in patients treated with combination therapy (1.03 (0.71, 1.51) mmol/l) compared to monotherapy (0.93 (0.67, 1.43) mmol/l) and was also associated with sex. There were significant differences in TG levels among the three genotypes of ApoA1 rs5072 (GG, GA, and AA) in the whole study population and in patients treated with atypical APDs.ConclusionThe ApoA1 rs5072 variant is associated with dysregulated TG metabolism in schizophrenia patients treated with APDs, which may increase susceptibility to dyslipidemia.
Project description:IntroductionHyperprolactinaemia, a common adverse effect of antipsychotic drugs, is primarily linked to blockade of dopamine D2 receptors in the pituitary gland. Certain antipsychotic drugs, such as, for example risperidone and paliperidone, are more likely to induce hyperprolactinaemia compared to others. This effect is probably caused by a relatively high blood/brain concentration ratio, a consequence of being a substrate of P-glycoprotein. Genetic variants of P-glycoprotein with changed functional activity might influence the potential of risperidone and paliperidone to cause hyperprolactinaemia as the altered blood/brain concentration ratio would lead to a reduced therapeutic drug level within essential brain areas making dose adaptations necessary. This increases exposure of dopamine D2 receptors within the pituitary gland.AimsTo investigate possible associations between MDR1/ABCB1 gene polymorphisms and antipsychotic drug-induced hyperprolactinaemia in Russian patients with schizophrenia and to determine possible differences between risperidone/paliperidone and other antipsychotics.MethodsIn total, 446 patients with schizophrenia were included from 3 psychiatric hospitals in Siberia. Blood samples were obtained in a cross-sectional study design for DNA extraction and prolactin measurement. Associations between hyperprolactinaemia and 8 MDR1/ABCB1 gene-polymorphisms were assessed using logistic regression analysis accounting for covariates. The analysis was repeated in a patient subgroup using risperidone or paliperidone.ResultsWe did not observe an association between any of the 8 single nucleotide polymorphisms and the prevalence of antipsychotic-induced hyperprolactinaemia in the total patient population. However, in the risperidone/paliperidone subgroup, the single nucleotide polymorphism rs2032582 (G2677T) was found to be negatively associated with risperidone/paliperidone-induced hyperprolactinaemia.ConclusionThis study revealed a significant association between the ABCB1 gene polymorphism rs2032582 (G2677T) and risperidone/paliperidone-induced hyperprolactinaemia.
Project description:Serotonin 2C receptors (5HT2C) are involved in serotonin-driven dynamic equilibrium adjustments responsible for homeostatic stability in brain structures that modulate behavior and emotions. Single nucleotide polymorphisms (SNPs) from the serotonin 2C receptor gene (HTR2C) have been associated with several neurological and mental disorders, including abnormalities in cognitive and emotional processes. The aim of this study was to evaluate the association between the rs6318 SNP of the HTR2C gene and behavioral characteristics exhibited by children and adolescents based on the Child Behavior Checklist (CBCL/6-18) inventory. Eighty-five psychiatric outpatients between 8 and 18 years of age underwent genotyping of the rs6318 SNP. The CBCL/6-18 scale was administered to their caregivers. The chi-squared test was used to assess differences in the frequency of C and G alleles of the rs6318 SNP relative to the grouped CBCL/6-18 scores; significance level was 5%. The presence of the G allele of rs6318 was found to be associated with characteristics of aggressive behavior and social problems, and aggressive behavior was found to be associated with heterozygosis in females. These findings contribute to the identification of mental and behavioral phenotypes associated with gene expression.
Project description:Schizophrenia (SCZ) is a chronic severe neuropsychiatric disorder, where pharmacological treatment has been hindered by adverse effects, including antipsychotic-induced weight gain (AIWG) and related complications. Genetic studies have been exploring the appetite regulation and energy homeostasis pathways in AIWG with some promising leads. The serotonin system has been shown to participate in these pathways.In the current study, we examined single nucleotide polymorphisms across the serotonin receptor genes HTR3A and HTR3B. Prospective weight change was assessed for a total of 149 SCZ patients of European ancestry.We did not find the tested HTR3A or HTR3B gene markers to be associated with AIWG in our sample.Our preliminary findings suggest that these receptors may not play a major role in predicting AIWG.
Project description:An insertion/deletion polymorphism in the promoter region of the serotonin transporter gene (5-HTTLPR) and a polymorphism (rs6313) in the serotonin 2A receptor gene (5-HT2A) have previously been linked to smoking behavior. The objective of this study was to determine the possible association of the 5-HTTLPR and 5-HT2A gene polymorphisms with smoking behavior within a population of Malaysian male smokers (n=248) and non-smokers (n=248). The 5-HTTLPR genotypes were determined using the polymerase chain reaction (PCR) and were classified as short (S) alleles or long (L) alleles. The 5HT2A genotypes were determined using PCR-restriction fragment length polymorphisms (PCR-RFLP). No significant differences in the distribution frequencies of the alleles were found between the smokers and the non-smokers for the 5-HTTLPR polymorphism (x(2) = 0.72, P>0.05) or the 5HT2A polymorphism (x(2) = 0.73, P>0.05). This is the first study conducted on Malaysian Malay males regarding the association of 5-HTTLPR and 5HT2A polymorphisms and smoking behavior. However, the genes were not found to be associated with smoking behavior in our population.
Project description:Second-generation antipsychotics (SGAs) are increasingly used in the treatment of many psychotic and nonpsychotic disorders. Unfortunately, SGAs are often associated with substantial weight gain, with no means to predict which patients are at greatest risk.To identify single-nucleotide polymorphisms associated with antipsychotic drug–induced weight gain.Pharmacogenetic association study.The discovery cohort was from a US general psychiatric hospital. Three additional cohorts were from psychiatric hospitals in the United States and Germany and from a European antipsychotic drug trial.The discovery cohort consisted of 139 pediatric patients undergoing first exposure to SGAs. The 3 additional cohorts consisted of 73, 40, and 92 subjects.Patients in the discovery cohort were treated with SGAs for 12 weeks. Additional cohorts were treated for 6 and 12 weeks.We conducted a genomewide association study assessing weight gain associated with 12 weeks of SGA treatment in patients undergoing first exposure to antipsychotic drugs. We next genotyped 3 independent cohorts of subjects assessed for antipsychotic drug-induced weight gain.Our genome-wide association study yielded 20 single-nucleotide polymorphisms at a single locus exceeding a statistical threshold of P<10(-5). This locus, near the melanocortin 4 receptor (MC4R) gene, overlaps a region previously identified by large-scale genome-wide association studies of obesity in the general population. Effects were recessive, with minor allele homozygotes gaining extreme amounts of weight during the 12-week trial. These results were replicated in 3 additional cohorts, with rs489693 demonstrating consistent recessive effects; meta-analysis revealed a genome-wide significant effect (P=5.59 X 10 (-12). Moreover, we observed consistent effects on related metabolic indices, including triglyceride, leptin, and insulin levels.These data implicate MC4R in extreme SGA-induced weight gain and related metabolic disturbances. A priori identification of high-risk subjects could lead to alternative treatment strategies in this population.
Project description:BACKGROUND: Several studies have hypothesized that genes regulating the components of the serotonin system, including serotonin transporter (5-HTTLPR) and serotonin 1 B receptor (5-HT1B), may be associated with alcoholism, but their results are contradictory because of alcoholism's heterogeneity. Therefore, we examined whether the 5-HTTLPR gene and 5-HT1B gene G861C polymorphism are susceptibility factors for a specific subtype of alcoholism, antisocial alcoholism in Han Chinese in Taiwan. METHODS: We recruited 273 Han Chinese male inmates with antisocial personality disorder (ASPD) [antisocial alcoholism (AS-ALC) group (n=120) and antisocial non-alcoholism (AS-N-ALC) group (n=153)] and 191 healthy male controls from the community. Genotyping was done using PCR-RFLP. RESULTS: There were no significant differences in the genotypic frequency of the 5-HT1B G861C polymorphism between the 3 groups. Although AS-ALC group members more frequently carried the 5-HTTLPR S/S, S/LG, and LG/LG genotypes than controls, the difference became non-significant after controlling for the covarying effects of age. However, the 5-HTTLPR S/S, S/LG, and LG/LG genotypes may have interacted with the 5-HT1B G861C C/C polymorphism and increased the risk of becoming antisocial alcoholism. CONCLUSION: Our study suggests that neither the 5-HTTLPR gene nor the 5-HT1B G861C polymorphism alone is a risk factor for antisocial alcoholism in Taiwan's Han Chinese population, but that the interaction between both genes may increase susceptibility to antisocial alcoholism.