D 1 And D 2 Receptors and circling behavior in rats with unilateral lesion of the entopeduncular nucleus

Abstract

The role of D 1 and D 2 striatal dopamine receptors on circling behavior was studied in a normosensitive model obtained by unilateral kainic acid lesion of the entopeduncular nucleus. In this model, the sensitivity of striatal dopamine receptors was preserved, because kainic acid destroyed the neurons of the entopeduncular nucleus and left undamage the fibers of passage and axon terminals. Systemic administration of SKF 38393 to these animals fails to induce circling activity. In contrast, administration of quinpirole elicited rotation toward the lesioned side, which was increased by concurrent injection of SKF 38393. This behavior was inhibited by pretreatment with either a specific D 1 (SCH 23390) or D 2 (-sulpiride) antagonist. The apomorphine also induced ipsilateral circling that was abolished by pretreatment with D 1 or D 2 antagonists. The above results suggest that coactivation of both D 1 and D 2 striatal dopamine receptors are necessary to induce rotation in this normosensitive model.