A CRITICAL ROLE FOR D-1 RECEPTORS IN THE 5-HT1A-MEDIATED FACILITATIONOF IN-VIVO ACETYLCHOLINE-RELEASE IN RAT FRONTAL-CORTEX

Subcutaneous administration of 8-OH-DPAT dose-dependently increased ac etylcholine (ACh) output in frontal cortex of awake rats. The maximal effect of 8-OH-DPAT (0.5 mg/kg, s.c.) was prevented by the 5-HT1A anta gonist WAY 100635 (1 mg/kg, s.c.) and by the D-1 antagonists SCH 23390 or SCH 39166 (both 0.3 mg/kg, s.c.) but not seven days after chemical lesion of the raphe serotoninergic neurons. It is postulated that the 8-OH-DPAT activation of postsynaptic 5-HT1A receptors enhances the re lease of dopamine which, by acting at D-1 receptors, stimulates the re lease of ACh in the frontal cortex.