A phosphoinositide-linked dopamine D1 receptor mediates repetitive jaw movements in rats.
BACKGROUND
We have demonstrated that rats injected with D1 agonists SKF 38393 or A68930 demonstrate repetitive jaw movements (RJM). These agonist-induced movements in rats are similar in their appearance to those induced in rats by long-term treatment with antipsychotic drugs. Over recent years D-1 receptors were discovered which showed linkage not only to c-AMP but also to PI hydrolysis. We examined the effect of EEDQ inactivation of D1 receptors on D-1 mediated PI hydrolysis and RJM.


METHODS
Twenty four hours following EEDQ or vehicle administration D-1 agonists or vehicle were administered. The number of RJM episodes was assessed in EEDQ and vehicle treated rats. D-1 receptor density and inositol phosphate formation were determined in the striata.


RESULTS
EEDQ administration resulted, 24 hours later, in 70-80% selective depletion of D-1 receptors in the striata but did not modify the rate of RJM induced by D-1 agonists. There was no significant difference in D-1 mediated PI hydrolysis in EEDQ treated rats when compared to vehicle treated group.


CONCLUSIONS
The present data support the earlier demonstration of D-1 agonist induced RJM, an effect mediated by a subpopulation of a D-1 receptor subtype and constitute the first behavioral evidence for the existence of a behavioral response mediated by D-1 like dopamine receptors linked to an alternate second messenger system-PI hydrolysis.
Rosengarten
H
H
Department of Psychiatry, Millhauser Laboratories, New York University School of Medicine, NY 10016, USA.
Friedhoff
A J
AJ
D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D007568:Jaw / Q000187:drug effects* / Q000502:physiology*; D008297:Male; D009068:Movement / Q000187:drug effects* / Q000502:physiology*; D010716:Phosphatidylinositols / Q000494:pharmacology*; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000187:drug effects*
D010716:Phosphatidylinositols; D017447:Receptors, Dopamine D1