STIMULATION OF MEDIAN, BUT NOT DORSAL, RAPHE 5-HT1A AUTORECEPTORS BY THE LOCAL APPLICATION OF 8-OH-DPAT REVERSES RACLOPRIDE-INDUCED CATALEPSY IN THE RAT

The local application of 8-OH-DPAT (0.5 or 2.5 mu g/rat, 10 min) into the median, but not the dorsal, raphe nucleus resulted in a reversal of the catalepsy induced by the DA D-2 receptor blocking agent raclopride (16mg kg(-1) s.c., 60 min). The local application of 8-OH-DPAT into serotonergic projection areas of the forebrain (dorso-lateral neostriatum, accumbens core; 0.5 or 2.0 mu g/side) did not affect raclopride-induced catalepsy. Thus, the 5-HT1A autoreceptor in the median raphe nucleus is an important site of action for the reversal of DA D-2 receptor antagonist-induced catalepsy by systemic administration of 5-HT1A receptor agonists, in the rat.