Differential effects produced by an anticholinergic on the neuroleptic inhibition of motor behaviour and self-stimulation of the prefrontal cortex in the rat.

A specific dopamine receptor blocker, spiroperidol (0.016, 0.032, 0.064 and 0.128 mg/kg) alone or in combined treatment with the centrally acting anticholinergic, dexetimide (0.5, 1.0 mg/kg) was given intraperitoneally to rats pressing a lever for brain self-stimulation through electrodes implanted in the medial prefrontal cortex. The same treatment was also given to rats in which the spontaneous motor behaviour was measured. Spiroperidol produced a dose-related inhibtion of both self-stimulation and spontaneous motor activity. Dexetimide, given to spiroperidol treated rats, was able to antagonize the motor impairment produced by spiroperidol, but prefrontal cortex self-stimulation remained decreased. These data support the suggested role for dopamine in self-stimulation of the prefrontal cortex in the rat.