DRD5 blocking peptide

Among the best-replicated and most heritable endophenotypes of attention-deficit/hyperactivity disorder (ADHD) are deficits in attention, inhibitory response control and larger intra-individual variability in response latencies. Here, we explored the presence of these heritable ADHD endophenotypes in two commonly used inbred mouse strains, C57BL/6J and DBA/2J, and investigated whether treatment with the stimulant amphetamine affected these phenotypes. Both in an operant Go/No-Go task and 5-choice serial reaction time (5-CSRT) task, DBA/2J mice showed reduced inhibitory response control compared with C57BL/6J mice. Mean correct response latencies of DBA/2J mice were slower in both tasks. Analysis of the distribution of correct response latencies suggested similar processing speed, but DBA/2J mice displayed larger intra-individual variability. Amphetamine did not affect inhibition in the Go/No-Go task but increased omission errors. In contrast, in the 5-CSRT task, amphetamine did not affect omission errors but impaired inhibitory response control, specifically in C57BL/6J mice. The dopamine uptake inhibitor, GBR 12909, mimicked this effect and decreased accurate choice, specifically in C57BL/6J mice, indicating that dopamine modulates inhibitory response control and attention in the murine 5-CSRT task Amphetamine did not affect response distributions in either task. Furthermore, we extended previous reports on differences in the brain dopamine system of DBA/2J and C578L/6J mice, by showing differential gene expression levels of three dopamine receptors (Drd1, Drd4 and Drd5) in the mPFC. In conclusion, genetic differences between DBA/2J and C57BL/6J mice translate into multiple ADHD-related phenotypes, indicating that these strains are valuable resources to understand genetic mechanisms underlying ADHD-relevant phenotypes. (C) 2010 Elsevier B.V. All rights reserved.

Background: Complex behaviors such as suicidal behavior likely exhibit gene-gene interactions. The main aim of this study is to explore potential single nucleotide polymorphisms combinations with epistatic effect in suicidal behavior using a data mining tool (Multifactor Dimensionality Reduction). Methods: Genomic DNA from peripheral blood samples was analyzed using SNPlex Technology. Multifactor Dimensionality Reduction was used to detect epistatic interactions between single nucleotide polymorphisms from the main central nervous system (CNS) neurotransmitters (dopamine: 9; noradrenaline: 19; serotonin: 23; inhibitory neurotransmitters: 60) in 889 individuals (417 men and 472 women) aged 18 years or older (585 psychiatric controls without a history of suicide attempts, and 304 patients with a history of suicide attempts). Individual analysis of association between single nucleotide polymorphisms and suicide attempts was estimated using logistic regression models. Results: Multifactor Dimensionality Reduction showed significant epistatic interactions involving four single nucleotide polymorphisms in female suicide attempters with a classification test accuracy of 60.7% (59.1%-62.4%, 95% CI): rs1522296, phenylalanine hydroxylase gene (PAH); rs7655090, dopamine receptor D5 gene (DRD5); rs11888528, chromosome 2 open reading frame 76, close to diazepam binding inhibitor gene (DBI); and rs2376481, GABA-A receptor subunit gamma 3 gene (GABRG3). The multivariate logistic regression model confirmed the relevance of the epistatic interaction [OR(95% CI) = 7.74(4.60-13.37)] in females. Conclusions: Our results suggest an epistatic interaction between genes of all monoamines and GABA in female suicide attempters. (C) 2012 Elsevier Inc. All rights reserved.