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Serotonin excites arcuate neurons directly but inhibits them through intercalated GABAergic neurons

Kang Yuming, Chen Jianyong, Ouyang Wei, Qiao Jiantian

Department of Neurobiology,Shanxi Medical University.Taiyuan 030001,Shanxi

Abstract

Effects of serotonin (5-HT) on spontaneous discharges of single hypothalamic arcuate neurons were observed in rat brain slices by extracellular recordings. The results showed that (1) of 149 neurons selected randomly and tested for 5-HT application, 33 (22.2%) were excited, 82 (55.0%) were inhibited, and 34 (22.8%) showed biphasic responses or failed to respond; (2) substitution of low Ca~(2+)-high Mg~(2+) artificial cerebrospinal fluid (aCSF) for normal aCSF abolished the 5-HT-induced inhibitory effect but failed to affect the 5-HT-induced excitatory effect; (3)cyproheptadine, a non-selective 5-HT receptor antagonist, could block either the 5-HT-induced excitatory or inhibitory effects in all neurons tested; and (4) bicuculline, a GABA_(A)-receptor antagonist, blocked the 5-HT0induced inhibitory effect.

Key words: Arcuate nucleus;Neurons;Serotonin;Cyproheptadine;Bicuculline;Brain slice

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Citing This Article：

Kang Yuming, Chen Jianyong, Ouyang Wei, Qiao Jiantian. Serotonin excites arcuate neurons directly but inhibits them through intercalated GABAergic neurons. Acta Physiol Sin 2002; 54 (3): (in Chinese with English abstract).