[A comparative study of the reinforcing and analgesic properties of cocaine].

During comparative studies of analgesic (writhing test) and reinforcing (place preference test) effects of cocaine, 5-40 mg/kg), the neurochemical dissociation of the effects of cocaine was found. Haloperidol, (0.06-1.0 mg/kg) inhibited cocaine-induced analgesia in a dose-dependent manner, but failed to influence cocaine-induced reinforcement. On the contrary, naloxone (0.25-1.0 mg/kg) inhibited cocaine-induced reinforcement, unaffecting drug-induced analgesia. The roles of opiatergic and dopaminergic systems in producing effects of cocaine are discussed.