Effects of chronic haloperidol and chlordiazepoxide treatment on lateral hypothalamic self-stimulation behavior in rats.

The effects of chronic administration of haloperidol and chlordiazepoxide for 14 days on self-stimulation behavior were investigated in rats with electrodes chronically implanted in the lateral hypothalamus. Haloperidol produced a prominent decrease in self-stimulation behavior during chronic treatment, followed by a significant increase in the lever-pressing rate during a 2 week withdrawal period, with a return to the control level about 5 weeks after drug withdrawal. Chlordiazepoxide produced a significant increase in self-stimulation behavior during chronic treatment. However, the lever-pressing rate was not significantly different from the control level during a 3 week observation period following drug withdrawal. These results indicate an increase in the sensitivity of central dopaminergic receptors following chronic haloperidol treatment, but not following chronic chlordiazepoxide treatment.