Serotonergic modulation of psychological stress-induced alteration in synaptic plasticity in the rat hippocampal CA1 field.
In order to elucidate possible involvement of the serotonergic neuronal system in the stress-induced alteration in synaptic plasticity, the effects of contextual fear conditioning (CFC) on long-term potentiation (LTP) in the hippocampal CA1 field were examined in 5-HT-depleted rats by pretreatment with 5,7-dihydroxytryptamine (5,7-DHT, 200 microg/rat, i.c.v.). LTP induction was suppressed by footshock (FS) stimulation in 5-HT-lesioned rats and vehicle-treated controls. When rats were exposed to CFC, which was received 24 h after FS stimulation, LTP was also blocked in both-treated groups. CFC-induced impairment of LTP, however, significantly attenuated in 5-HT-lesioned rats when compared with that in controls. Fear-related freezing behavior after FS stimulation occurred similarly in both treated groups, whereas the behavior observed during exposure to CFC significantly reduced in 5-HT-lesioned rats. These results suggest that the serotonergic mechanism is involved in the psychological stress-induced alteration in synaptic plasticity, which appears to be associated with fear-related behavior.
Matsumoto
Machiko
M
Department of Neuropharmacology, Hokkaido University Graduate School of Medicine, Kita-15, Nishi-7, Kita-ku, Sapporo 060-8638, Japan. mbird@med.hokudai.ac.jp
Togashi
Hiroko
H
Ohashi
Satoshi
S
Tachibana
Kaori
K
Yamaguchi
Taku
T
Yoshioka
Mitsuhiro
M
D015116:5,7-Dihydroxytryptamine / Q000494:pharmacology; D000818:Animals; D019540:Area Under Curve; D003213:Conditioning, Psychological; D004307:Dose-Response Relationship, Radiation; D004558:Electric Stimulation; D005239:Fear; D006624:Hippocampus / Q000166:cytology / Q000503:physiopathology*; D017774:Long-Term Potentiation / Q000187:drug effects / Q000502:physiology / Q000528:radiation effects; D008297:Male; D009473:Neuronal Plasticity / Q000502:physiology*; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D012701:Serotonin / Q000378:metabolism*; D013315:Stress, Psychological / Q000503:physiopathology*; D013569:Synapses / Q000187:drug effects / Q000502:physiology*; D013997:Time Factors
D015116:5,7-Dihydroxytryptamine; D012701:Serotonin