A PHOSPHOINOSITIDE-LINKED DOPAMINE D1 RECEPTOR MEDIATES REPETITIVE JAW MOVEMENTS IN RATS

Background: We have demonstrated that rats injected,with DI agonists S KF 38393 or A68930 demonstrate repetitive jaw movements (RJM). These a gonist-induced movements in rats are similar in their appearance to th ose induced in mts by long-term treatment with antipsychotic drugs. Ov er recent pears D-1 receptors were discovered which showed linkage not only to c-AMP but also to PI hydrolysis. We examined the effect of EE DQ inactivation of D1 receptors on D-1 mediated PI Hydrolysis and RJM, Methods: Twenty four hours following EEDQ or vehicle administration D -I agonists or vehicle were administered. The number of RJM episodes w as assessed in EEDQ and vehicle treated rats. D-I receptor density and inositol phosphate formation were determined in die striata. Results: EEDQ administration resulted 24 hours later; in 70-80% selective depl etion of D-1 receptors in the striata brit did not modify the rate of RJM induced by D-I agonists, There was no significant difference in D- I mediated PI hydrolysis in EEDQ treated rats when compared to vehicle treated group. Conclusions: The present data support the earlier demo nstration of D-1 agonist induced RJM, art effect mediated by a subpopu lation of a D-1 receptor subtype and constitute the first behavioral e vidence for the existence of a behavioral response mediated by D-I lik e dopamine receptors linked to an alternate second messenger system-PI hydrolysis. (C) 1998 Society of Biological Psychiatry.