Endogenous dopamine modulates corticopallidal influences via GABA.

Acute experiments on Sprague-Dawley rats were performed to study the effects of local application of D1 and D2 receptor antagonists (SCH 23390 and raclopride) on the responses of neurons in the globus pallidus induced by stimulation of the somatosensory cortex. SCH 23390 induced short-latency inhibition in response to stimulation of the cortex and blocked long-latency inhibition. Application of raclopride suppressed short-latency inhibition and induced a long-latency inhibitory response to stimulation of the cortex. It is suggested that these changes are based on modulation of GABA release from striopallidal terminals by endogenous dopamine.