D-CYCLOSERINE DECREASES BOTH D-1 AND D-2 DOPAMINE-RECEPTORS NUMBER AND THEIR FUNCTION IN RAT-BRAIN

Twenty-four hours after the implantation of the transstriatal probe D-cycloserine (3 mg/kg IP), a partial agonist of the strychnine-insensitive NMDA-associated glycine recognition site failed to change DA and DOPAC extracellular output in rat striatal dialysates. In extensively washed synaptic plasma membranes prepared both from cortices or striata of rats treated with D-cycloserine [H-3]-MK 801 specific binding was increased. In contrast, in striatal membranes the B-max values of both [H-3]-SCH 23390 and [H-3]-spiroperidol bindings to D-1 and D-2 dopamine receptors were decreased. Parallel decreases both of grooming behavior induced by the D-1 agonist SKF 38393 (10 mg/kg IF) and of the hyperactivity elicited by the D-2 agonist LY 171555 (0.3 mg/kg IP) in rat were observed.