Activation of postsynaptic D2 dopamine receptors in the rat dorsolateral striatum prevents the amnestic effect of systemically administered neuroleptics.

Systemically administered antipsychotics bind to dopamine (DA) D2 receptors expressed in both pre- and postsynaptic neurons of different striatal sites and present an amnestic effect on learning and memory of conditioned avoidance responses (CAR). The aim of this study was to test whether blockade of the pre- or post-synaptic D2 receptors of the dorsolateral striatum of rats is the mechanism by which systemically administered antipsychotics present this amnestic effect. CAR learning and memory was evaluated in rats that received i.p. administrations of pre- or postsynaptic doses of the antipsychotic sulpiride combined with intra-DLS infusion of the D2 agonist quinpirole. Intra-DLS quinpirole itself was not amnestic and this effect was prevented by co-administration of presynaptic dose of sulpiride. However, sulpiride was amnestic when administered systemically in a post- but not presynaptic dose. This amnestic effect of sulpiride was prevented by the co-administration of quinpirole into the DLS. These results show that a blockade of postsynaptic D2 receptors in the DLS is necessary and sufficient to produce the amnestic effect of neuroleptics on CARs.