Apomorphine-induced changes in striatal and pallidal neuronal activity are modified by NMDA and muscarinic receptor blockade

Systemic administration of apomorphine decreased the firing rate of caudate Type I neurons and increased the firing rate, presumably via disinhibition (16), of globus pallidus (GP) Type II neurons. In the present study, extracellular single-unit recording techniques were used to demonstrate that systemic administration of the NMDA antagonist dizocilpine (MK801) reduced both the inhibition of caudate neurons by apomorphine as well as the apomorphine-induced excitation of GP neurons. In addition, the muscarinic antagonists atropine and scopolamine had effects similar to dizocilpine. Thus, both glutamate and acetylcholine appear to play a role in dopaminergic modulation of striatal and GP activity.