Reversal of haloperidol induced deficits in self-stimulation by anti-Parkinsonian drugs.

The effects of 0.1 mg/kg dose of haloperidol on self-stimulation were assessed in rats having 3 stable self-stimulation response rates of approximately 10, 50 and 100 responses per min generated by 3 levels of current intensity. Haloperidol reduced overall response rates at all current intensities and generated extinction-like response patterns. Concurrent anti-Parkinsonian (benztropine 4.0 mg/kg or diphenhydramine 4.0 mg/kg) eliminated the within session extinction performance pattern and at the highest current intensity benztropine restored self-stimulation to a non-drug performance level. These results suggested that haloperidol induced impairments in self-stimulation are secondary to a motoric rather than reinforcement dysfunction.