This preliminary study, which will be of 2 years duration, will assess the relationship between changes in gene-expression induced by treatment with progesterone and laboratory measures of stress-induced craving, negative emotion, and physiology previously shown to predict risk for early relapse in cocaine addicted subjects. The long-term goal of this project is to develop novel molecular tools that can be used to predict and monitor the response to specific treatments for cocaine dependence. Preliminary studies have shown that men and women differ in their subjective and physiological responses to cocaine, as well as stress or drug-cue related stimuli associated with risk for relapse. Men and women also differ in their clinical response to various proposed pharmacological treatments for cocaine addiction. Differences in the level of gonadal steroids may underlie some or all of these differences. Recently, a number of small scale laboratory investigations and clinical trials have investigated progesterone as a possible treatment for cocaine addiction. Studies in animal models have shown that progesterone receptors are widely expressed in the brain and regulate the expression of a large number of genes in the brains of both female and male animals. In addition, progesterone has been shown to activate both the ERK/CREB/bcl-2 and Akt second messenger signaling pathways in neurons. These effects have been proposed to underlie the neuroprotective actions of progesterone in several experimental models. Activation of these pathways may oppose the actions of stress-induced patterns of gene expression, which could mediate increased risk for relapse in cocaine dependent individuals. In this study, we will recruit (n=60;30 male and 30 female) treatment-seeking cocaine-dependent subjects who are currently being recruited to take part in a NIDA-funded study of progesterone effects on stress and cue- induced cocaine craving and relapse susceptibility. In that study, subjects are randomly assigned to receive either progesterone (400mg/day) or placebo for a period of five days and undergo brief guided imagery sessions involving personalized stressful, drug-cue or neutral-relaxing situations (one imagery condition per session). In the proposed study, we will isolate RNA from blood collected prior to treatment and on day 5 of treatment with either progesterone or placebo. Gene-expression levels will be assessed by microarray hybridization using Illumina Sentrix Beadchip (Human-6v2) arrays (the same platform used in our preliminary studies). Gene-expression levels will be correlated with drug craving, anxiety and emotion ratings, as well as behavioral distress responses, heart rate, blood pressure, and salivary cortisol measures assessed during each session. Differential expression of selected genes of interested will be confirmed using Quantitative real-time reverse transcription polymerase chain reaction (qRT-PCR).
Specific aims i nclude: (1) comparing progesterone-induced changes in peripheral blood gene-expression in cocaine-dependent men and women;and (2) identifying specific progesterone-regulated transcripts whose expression is correlated with the subjective response to stress or drug-cue related stimuli.
These studies will allow us to better understand the molecular basis for individual differences in the response to progesterone in cocaine dependent men and women. Better understanding of these differences will allow us to identify those individuals (both men and women) most likely to benefit from treatment with progesterone. In addition, better understanding of the mechanism of action of progesterone at the genomic level may help to guide the development of novel hormonally based pharmacotherapies for the treatment of cocaine dependence.
