5-HT1A receptor agonist affects fear conditioning through stimulations of the postsynaptic 5-HT1A receptors in the hippocampus and amygdala.

Full Abstract

Evidence from preclinical and clinical studies has shown that 5-HT(1A) receptor agonists have anxiolytic actions. The anxiolytic actions of 5-HT(1A) receptor agonists have been tested by our previous studies using fear conditioning. However, little is known about the brain regions of anxiolytic actions of 5-HT(1A) receptor agonists in this paradigm. In the present study, we investigated the effects of bilateral microinjections of flesinoxan, a selective 5-HT(1A) receptor agonist, into the hippocampus, amygdala and medial prefrontal cortex on the expression of contextual conditioned freezing and the defecation induced by conditioned fear stress in rats. These results reveal that both intrahippocampal and intraamygdala injections of flesinoxan decreased the expression of conditioned freezing, while injections into the medial prefrontal cortex did not. In addition, intraamygdala injection of flesinoxan attenuated the increased defecation induced by conditioned fear, but injections into the hippocampus and medial prefrontal cortex failed. These results suggest that flesinoxan exerts its anxiolytic actions in the fear conditioning through stimulations of the postsynaptic 5-HT(1A) receptors in the hippocampus and amygdala.

Author information

Author/s: Li, XiaoBai (X); Inoue, Takeshi (T); Abekawa, Tomohiro (T); Weng, ShiMin (S); Nakagawa, Shin (S); Izumi, Takeshi (T); Koyama, Tsukasa (T);

Affiliation: Department of Psychiatry, Neural Function, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan.

Journal and publication information

Publication Type: Journal Article; Research Support, Non-U.S. Gov't

Journal: European journal of pharmacology (Eur J Pharmacol), published in Netherlands. (Language: eng)

Reference: 2006-Feb; vol 532 (issue 1-2) : pp 74-80

Dates: Created 2006/02/28; Completed 2006/06/02; Revised 2006/11/15;

PMID: 16460727, status: MEDLINE (last retrieved date: 2/18/2009)

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