The overall goal of the original application is to determine in both males and females the conditions that produce a progressive increase, or incubation, of cocaine-seeking and taking behaviors that occur following abstinence from extended access self-administration and to characterize the underlying neurobiology. In this supplement, we will expand upon the original application by examining conditions that retard this """"""""incubation effect"""""""". Specifically, in this supplement, we will test the hypothesis that aerobic exercise (i.e., wheel running) during abstinence will prevent the occurrence of incubation of cocaine-craving and associated neuroadaptations after extended access cocaine self-administration. Therefore, the primary goal of this supplement is to determine the potential utility of exercise as an intervention during relapse. As a secondary objective, we will also determine the effects of aerobic exercise on the underlying neurobiological changes that occur during an abstinence period, and like the original application, we will focus on neuroadaptations in dopaminergic and glutamatergic signaling in the nucleus accumbens and medial prefrontal cortex, two regions implicated in cocaine addiction. Given known differences between males and females in the time-course for the development of addiction, and based on an emerging literature that highlights the need the use of sex-specific interventions, a third objective is to determine if males and females respond differently to exercise as an intervention. This application has one specific Aim that is seen as the fourth aim to the original application. Specifically, the aim of this supplement is to determine the effects of aerobic exercise on cocaine reinstatement and its underlying neurobiology as a function of sex and hormonal status. To satisfy this aim, cocaine reinstatement will be examined under both cue-induced and stress-induced conditions following extended access cocaine self-administration and an extended abstinence period whereby rats will either have 2 hrs/access to a wheel or no access. Markers of dopamine (i.e., total and phosphorylated levels of tyrosine hydroxylase and dopamine and cAMP-regulated phosphoprotein of 32 kDa (DARPP-32)), glutamate (i.e., total and phosphorylated levels of NR1 and GluR1), and extracellular signal-regulated kinase signaling will be examined in the nucleus accumbens and medial prefrontal cortex of rats 2-weeks after extended access cocaine using Western Blot analysis. As part of the proposed research, we plan to correlate behavioral, hormonal, and molechemical data to help identify biological characteristics that may retard cocaine relapse. These proposed supplemental studies test the stated ultimate goal of the parent grant to identify potential interventions that can be tailored for men and women.
Our study is significant because it focuses on determining efficacy and biological basis for exercise as a potential intervention for cocaine addiction in males and females. The overall goals of this basic science work is to help determine whether exercise would be a useful intervention for cocaine addiction, and to provide information that may guide the development of even more effective sex-specific interventions.
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