Bromocriptine promotes recovery of self-stimulation in 6-hydroxydopamine-lesioned rats

Rats with stable self-stimulation response rate-current intensity functions were subjected to bilateral 6-hydroxydopamine injections into the substantia nigra. The effect of several drug treatments were evaluated on the 6-hydroxydopamine lesion self-stimulation deficit. d-Amphetamine (1.0, 2.0 and 3.0 mg/kg) and scopolamine (0.25, 0.5 and 1.0 mg/kg) had little or no effect on self-stimulation, but bromocriptine (2.0 and 4.0 mg/kg) produced a nearly complete recovery of self-stimulation performance. In contrast, scopolamine increased locomotor activity: whereas, bromocriptine did not increase activity. These results point up the efficacy of bromocriptine in reversing self-stimulation deficits induced by a dopamine deficiency, and indicate that self-stimulation may be a more useful behavior than locomotor activity for evaluating drugs which might alleviate Parkinsonism.