Supraspinal mediation of dopamine-serotonin interactions in extrapyramidal motor functions in the rat.

The effects of intracerebroventricularly (i.c.v.) or intrathecally (i.t.) administrated 8-OH-DPAT on catalepsy, induced by the specific DA D2 antagonist raclopride (16 mg kg-1 s.c.), were studied in rats. It was found that 8-OH-DPAT (0.5 or 2.0 micrograms kg-1) injected by the i.c.v. route produced a statistically significant of raclopride-induced catalepsy at both doses. In contrast, 8-OH-DPAT (0.2 or 2.0 micrograms kg-1) given by the i.t. route had no statistically significant effect on the raclopride-induced catalepsy. These results suggest that the antagonistic effect of 8-OH-DPAT on catalepsy, induced by DA blocking agents, is primarily mediated at the supraspinal level.