Effects of Baclofen on Cue-induced Reinstatement of Cocaine Self-Administration

Thesis advisor: Stephen C. HeinrichsThis study investigated the effects of baclofen, a GABAB agonist, on modulating drug seeking and drug reward in a novel model of reinstatement. To investigate drug seeking, rats were trained to nosepoke for cocaine infusions, given a drug holiday, and under a baclofen pretreatment (0, 0.2, 1, or 5 mg/kg i.p.), were exposed to an odor conditioned discriminative stimulus (DS+) that reinstated cocaine self-administration. To investigate drug reward, an odor reactivity test was used. Rats were tested for changes in odor preference after the acquisition, drug holiday, and reinstatement phases of self-administration behavior were each completed. Pretreatment with the low dose of baclofen (0.2) attenuated cocaine seeking primed by a conditioned DS+. Medium doses (1.0) caused no change in drug seeking. High doses (5.0) caused a reduction in drug seeking, but this was due to motor impairment. No doses of baclofen had any affect on the rewarding properties of cocaine or cocaine-associated stimuli. It can be concluded that GABAB receptors have no role in modulating the rewarding properties of drug rewards or drug-associated stimuli, but instead play a role in modulating drug seeking. In rats that were exposed to a drug in the past, low levels of GABAB receptor activation reduce drug-seeking, while medium to high levels could have reduced dopamine levels to the point that increased drug seeking or motor impairment was seen.Thesis (BA) — Boston College, 2004.Submitted to: Boston College. College of Arts and Sciences.Discipline: Psychology.Discipline: College Honors Program