Plasticity of responses to synaptic inputs in rat ventral striatal neuronsafter repeated administration of the dopamine D2 antagonist raclopride

The effects of acute and repeated systemic administration of the dopaminerg ic D2 antagonist raclopride on responses of ventral striatal neurons were e xamined in chloral hydrate-anesthetized rats. Stimulating electrodes were p laced in the entorhinal and perirhinal cortices, medial thalamus, and preli mbic cortex. Stimulation in water-injected control rats evoked one or occas ionally two action potentials. Results were similar in rats injected acutel y with raclopride (4 or 8 mg/kg) except that a small proportion of cells (5 %) produced burst responses (defined as three or more evoked action potenti als). In rats injected with raclopride daily for 7-14 days, burst responses were seen in a larger proportion of cells (17%) and bursts of up to nine a ction potentials could be evoked. The results suggest that repeated adminis tration of dopaminergic agents can induce striking plastic changes of excit atory responses in a subset of ventral striatal neurons. Synapse 32:297-301 , 1999, (C) 1999 Wiley-Liss, Inc.