A SUBPOPULATION OF DOPAMINE-D(1) RECEPTORS MEDIATE REPETITIVE JAW MOVEMENTS IN RATS

Repetitive jaw movements (RJM) in rats, a potentially useful animal mo del of tardive dyskinesia, appears to be mediated by the dopamine D1 r eceptor as evidenced in part by their induction and inhibition with D1 agonists and D1 antagonists, respectively. Selective destruction of 6 0-90% of D1 receptors by EEDQ, measured in several CNS dopaminergicall y innervated areas, preceded by protection of D2, 5-HT2, alpha1 and al pha2 receptors, however, failed to reduce D1 agonist-augmentable RJM. Further, the affinity of dopamine toward displacement of H-3-SCH-23390 binding from striatal D1 receptors was significantly decreased by adm inistered EEDQ, a counter-intuitive result in relation to D1 responsit ivity and RJM. Thus, at present it is suggested that an EEDQ-resistant D1 receptor subpopulation may exist.