Serotonergic modulation of acetylcholine release in the rat dorsal hippocampus

• Published in: Japanese Journal of Pharmacology 1993, Vol.61 (suppl.1), p.113-113
• Main Authors: Izumi, Junkichi, Washizuka, Masataka, Miura, Naoyoshi, Hiraga, Yoshihiro, Ikeda, Yugo
• Format: Article
• Language: eng ; jpn
• ISSN: 0021-5198
• DOI: 10.1016/S0021-5198(19)51358-0

We investigated the changes in acetylcholine (ACh) release following local application of serotonergic agents by means of perfusion with microdialysis technique in conscious rats. Perfusion of serotonin (5-HT, 10μM, 30min), dissolved in Ringer's sol. containing 10μM of eserine, showed no marked effect on the extracellular level of ACh. 8-OH-DPAT(20μM), a 5-HT_1A agonist, increased the ACh level, while CGS12066B(100μM), a 5-HT_1B agonist, decreased it. Clomipramine(2μM), an uptake inhibitor of 5-HT, had no effect on ACh level. Following perfusion of NAN-190(100μM), a 5-HT_1A antagonist, CGS-12066B decreased the level of ACh, but the effect of 8-OH-DPAT was diminished. 5-HT had a decreasing effect on ACh level after pretreatment with NAN-190, as well as clomipramine. These results indicate that the mechanism of serotonergic modulation of ACh release partly depends on both the positive input via 5-HT_1A receptor and the negative input via 5-HT_1B receptor in the dorsal hippocampus of rats. Furthermore, the existence of 5-HT_1B receptor on the nerve terminal of cholinergic neuron is postulated.