ENDOGENOUS CANNABINOIDS AS AN AVERSIVE OR COUNTER-REWARDING SYSTEM INTHE RAT

Human use of marijuana (Cannabis sativa) is widely assumed to have rew arding properties, a notion supported by its widespread recreational u se. However, no study has clearly demonstrated such effects in animal models. The purpose of this study was to test for the presumed rewardi ng effect of cannabinoids using a conditioned place preference paradig m. The results showed that animals failed to develop place conditionin g ata low dose (1.5 mg/kg) and developed a place aversion at a high do se (15 mg/kg) of the active principle in marijuana, bg-tetrahydrocanna binol (Delta(9)-THC), a finding consistent with most previous studies. Moreover, the administration of the cannabinoid antagonist SR141716A induced a conditioned place preference at both a low (0.5 mg/kg) and a high (5 mg/kg) dose. In summary, cannabinoid antagonism produced plac e preference while cannabinoid agonism induced place aversion. These r esults suggest that endogenous cannabinoids serve normally to suppress reward or to induce aversion. (C) 1997 Elsevier Science Ireland Ltd.