Effect of opioid and cannabinoid receptor antagonism on orphanin FQ-induced hyperphagia in rats.

Feeding induced in rats by cerebroventricular (i.c.v.) injection of orphanin FQ was potently and dose-dependently reversed by peripheral injection of either the opioid antagonist naloxone or the cannabinoid CB(1) receptor antagonist SR 141716[N-piperidino-5-(4-chlorophenyl)-1-(2,4-dichlorophelyl)-4-methyl-3-pyrazole-carboxamine]. The combination of these two agents inhibited food intake in a manner suggestive of additivity or supra-additivity.