Stimulatory effect of acetylcholine on immunoreactive corticotropin-releasing factor release from the rat hypothalamus in vitro

Abstract Effects of acetylcholine (Ach) and γ-aminobutyric acid (GABA) on immunoreactive corticotropin-releasing factor (CRF) release from the rat hypothalamus were examined using a rat hypothalamic perifusion system and a rat CRF RIA in vitro. Ach stimulated CRF release in a dose-dependent manner (1 pM-1 nM). One nM Ach-induced CRF release was inhibited by atropine in a dose-dependent manner (1–100 nM), but was inhibited by only a high concentration (100 nM) of hexamethonium. In addition, such Ach-induced CRF release was inhibited by norepinephrine. GABA did not influence basal CRF release. These results suggest that Ach stimulates CRF release mainly through muscarinic receptors at least under our conditions.