5-HT1A receptor agonist affects fear conditioning through stimulations of the postsynaptic 5-HT1A receptors in the hippocampus and amygdala.
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.
Li
XiaoBai
X
Department of Psychiatry, Neural Function, Hokkaido University Graduate School of Medicine, North 15, West 7, Kita-ku, Sapporo, 060-8638, Japan.
Inoue
Takeshi
T
Abekawa
Tomohiro
T
Weng
ShiMin
S
Nakagawa
Shin
S
Izumi
Takeshi
T
Koyama
Tsukasa
T
D000679:Amygdala / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects; D003213:Conditioning, Psychological / Q000187:drug effects*; D005239:Fear / Q000187:drug effects* / Q000523:psychology; D006624:Hippocampus / Q000033:anatomy & histology / Q000187:drug effects* / Q000502:physiology; D008297:Male; D008845:Microinjections; D009043:Motor Activity / Q000187:drug effects; D010879:Piperazines / Q000008:administration & dosage / Q000494:pharmacology*; D017397:Prefrontal Cortex / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley; D044282:Receptor, Serotonin, 5-HT1A / Q000502:physiology; D058825:Serotonin 5-HT1 Receptor Agonists; D017366:Serotonin Receptor Agonists / Q000008:administration & dosage / Q000494:pharmacology; D013569:Synapses / Q000187:drug effects / Q000502:physiology
D010879:Piperazines; D058825:Serotonin 5-HT1 Receptor Agonists; D017366:Serotonin Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; C056895:flesinoxan