David A. Nielsen, Ph.D. - US grants

[unreadable] DESCRIPTION (provided by applicant): In the United States, drug addiction is a major medical problem and has significant implications for public health and society with over one million people addicted to heroin. Physiological systems are disrupted by drugs of abuse, and these disruptions contribute to drug addiction and relapse. Epidemiological studies have indicated that non-genetic factors contribute 50-80% of the risk of developing addiction. Among these non- genetic factors are epigenetic factors which include methylation of cytosines that reside in cytosine:guanine (CpG) dinucleotides in genomic DNA. This common epigenetic mechanism is known to repress gene expression. Methylated DNA recruits methyl-CpG repressor protein and enzymes responsible for altering histones, both repressing gene expression probably through the inhibition of transcription factor binding. Furthermore, methylation is important in the expression of imprinted genes and in the development of some cancers. Although methylation patterns are mostly stable after birth, exogenous factors, such as dietary factors, can alter DNA methylation state and transcriptional activity. In addition, the chromatin structure of several promoters has been shown to be altered by cocaine (dependent on the treatment regime). We hypothesize that DNA methylation patterns in the promoter regions of genes known to be involved in the effects of drugs of abuse, or associated with predisposition to drug abuse, will differ between former opiate addicts (without or without cocaine addiction) and controls. This difference in the methylation patterns may be due to the drug addiction itself or due to a predisposition to drug abuse. In this application we propose to 1) study the DNA methylation patterns in former opiate addicts (without or with cocaine addiction) and control subjects and 2) if a methylation state difference is found, analyze the expression of these genes in lymphocytes from former severe opiate addicts and controls. The identification of a methylation state difference and a relation of this methylation pattern to expression between addicted patients and controls would be a provocative and exciting finding that would lead to future studies. An understanding of this epigenetic mechanism in heroin addiction is essential and may lead to the elucidation of novel pharmacotherapies for the treatment of opiate addiction. Findings of the studies in this application may help to alleviate individual suffering and the tremendous cost to society caused by drug and alcohol addiction. [unreadable] [unreadable] [unreadable]

The Pharmacogenetics CORE integrates molecular genetics into the design and execution of the drug administration and clinical trials of pharmacotherapies for cocaine and methamphetamine dependence. The CORE will provide DNA isolation and DNA genotyping of cocaine- or methamphetamine-dependent patients from ongoing and completed clinical pharmacotherapy trials. Genetic variants and copy number variants (CNVs) will be analyzed for significant associations with response to pharmacotherapeutic treatment regimes. DNA samples will be evaluated for associations of 1) single nucleotide polymorphisms (SNPs), 2) copy number variants (CNVs), and 3) insertion/deletion variants with response to pharmacotherapy. As indicated in our Preliminary Data, we have started the examination ofthe CNVs. Searches ofthe literature and of bioinformatic databases will be conducted to translate the findings about the genetic associations with pharmacological responses into human studies. Genes with significantly associated variants identified from the bioinformatic searches will then be used in prospective pharmacogenetic selection of patients for the matching of these patients to the most appropriate of many available potential anti-addiction medications for further placebo controlled testing in either human laboratory drug administration or clinical trial studies.

DESCRIPTION (provided by applicant): This grant responds to "NIH Announces the Availability of Recovery Act Funds for Competitive Revision Applications" (NOT-OD-09-058). We propose a novel yet hypothesis-based approach to examine sex differences in stress responsivity and addiction using established procedures. Stress responsivity relates to acquisition of drug self-administration, a model of addiction vulnerability, and both shows sex differences. Links between maternal care and stress responsivity of offspring are established;greater care relates to lower stress responsivity in adults. Further, these effects are mediated via epigenetic mechanisms. Maternal care differs by pup sex;males receive more care than females. Consistent with the link of maternal care with stress responsivity, adult males show lower stress responsivity than females. We hypothesize that sex-dependent maternal care influences sex differences in stress responsivity and cocaine self-administration reflecting altered DNA methylation of specific genes (e.g., Gr17, Bdnf) in select brain areas (e.g., NAc, PFC, and hippocampus). We will test this by manipulating maternal care via altering litter gender composition (LGC;single- vs mixed-sex litters). LGC influences stress responsivity in infant mice and juvenile and maternal behaviors in rats and mice. Both male and female adult rats of single-sex litters are predicted to show lower stress responsivity than offspring of mixed-sex litters. In Specific Aim 1, we will confirm prior studies demonstrating sex-specific effects of maternal care. We will measure stress hormone levels to stressors and assess glucocorticoid feedback sensitivity. We predict the following effects of LGC on stress responses: mixed females>single females >=mixed males>single males. The relationship between stress responsivity and drug self-administration is complex and may be non-linear;both low and high stress responsivity may associate with low responding. Thus, we predict LGC will attenuate cocaine self-administration in mixed females and single males resulting in an inverted U-shaped function of stress responsivity to cocaine self-administration. Studies in Specific Aim 2 will test effects of LGC on acquisition of cocaine self-administration and food responding. Specific Aim 3 will address epigenetic contributions to these sex differences by assessing DNA methylation patterns of targeted genes in brain regions associated with stress responsivity and drug self-administration. Data will inform on the role of maternal care and underlying epigenetic mechanisms that contribute to sex differences in stress responsivity and addiction. PUBLIC HEALTH RELEVANCE: The goal of this research is to achieve a better understanding of sex differences in stress responsivity and vulnerability to addiction. Studies in this competitive revision will test the hypothesis that these sex differences are due to sex-dependent differences in maternal care received and reflect epigenetic effects of targeted genes in select brain regions.