DURATION OF CATALEPSY CORRELATES WITH INCREASED INTRASTRIATAL SULPIRIDE

To investigate the mechanism underlying sulpiride-induced catalepsy, w e simultaneously examined cataleptic behavior and the kinetics of the dopamine receptor antagonist, sulpiride of dopamine, and the dopamine metabolite 3,4-dihydroxyphenylacetic acid (DOPAC), using in vivo volta mmetry. After intrastriatal administration of sulpiride to freely movi ng rats, the levels increased, peaked at 20 min, and remained elevated for more than 3 h. Sulpiride-induced cataleptic behavior also continu ed for 3 h. Levels of DOPAC peaked 180 min after the injection and did not return to baseline within the experimental period. Thus, the time -course of cataleptic behavior correlated better with elevated extrace llular levels of sulpiride than with that of DOPAC. These findings sug gest that sulpiride induces catalepsy via a direct action.