Enhanced dopamine release in the dorsolateral caudate putamen during relapse as a function of previous cocaine self-administration history

GABRIELE A; PACCHIONI A; SEE R

Scottsdale, Arizona

Congreso; 72nd Annual Meeting of the College on Problems of Drug Dependence; 2010

College on Problems of Drug Dependence

Aims: Growing evidence suggests that persisting neuroadaptive changes occurwith prolonged cocaine use, whereby the dorsal striatum comes to exert greatercontrol over cocaine-seeking behavior. The current study investigated striataldopamine (DA) release in the dorsolateral caudate putamen (dlCPu) at the timeof relapse following abstinence in rats that experienced short or long daily accessto cocaine self-administration. We hypothesized that animals receiving longaccess cocaine self-administration would show enhanced striatal DA release atthe time of relapse.Methods: Male Sprague-Dawley rats (n= 20) were trained to self-administer i.v.cocaine (0.2 mg/50 ul infusion) for 6 days (2 hr sessions). Animals were thenswitched to one of two access conditions: short access (2 hr/5 days) or long access(6 hr/15 days). Following completion of self-administration, animals underwenttwo relapse tests and concurrent microdialysis in the self-administration contextafter 24 hr and 14 days of abstinence. Microdialysis probes (2 mm) were insertedinto the dlCPu and basal samples were collected at 20 min intervals for 1 hrprior to testing and throughout the 2 hr context relapse session. Samples wereanalyzed for extracellular DA levels using HPLC and electrochemical detection.Results: Results indicate increased DA release in the dlCPu at relapse in animalsthat received long access cocaine as compared to short access cocaine (p