Juvenile stress attenuates the dorsal hippocampal postsynaptic 5-HT1A receptor function in adult rats.
BACKGROUND
Traumatic events in early life are associated with an increased risk of psychiatric diseases in adulthood. 5-hydroxytryptamine (5-HT)(1A) receptors play a pivotal role in the 5-HTergic mechanisms associated with the etiology of stress-related disorders.


OBJECTIVE
The goal of the present study was to investigate whether juvenile stress influences emotional control via postsynaptic 5-HT(1A) receptor in the hippocampus and amygdala using contextual fear conditioning test in adult rats.


METHODS
The rats were subjected to aversive footshock (FS) during the third week of the postnatal period (3wFS group). During the postadolescent period (10-14 weeks postnatal), experiments were performed.


RESULTS
The systemic administration of the 5-HT(1A) receptor agonist R-(+)-8-hydroxy-2-(di-n-propylamino) tetralin (8-OH-DPAT) (0.2 mg/kg, i.p.) attenuated the freezing behavior in the non-FS group, but not in the 3wFS group. The bilateral local injection of 8-OH-DPAT (1 μg/side) into the amygdala decreased the freezing behavior in the non-FS group and the 3wFS group. However, the local injection of 8-OH-DPAT (1 μg/side) into the hippocampus decreased the freezing behavior in the non-FS group, but not in the 3wFS group. In a 5-HT(1A) receptor binding study, the Bmax of the 3wFS group decreased in the dorsal hippocampus, but not the amygdala in comparison with the non-FS group.


CONCLUSIONS
The juvenile stress attenuated the hippocampal postsynaptic 5-HT(1A) receptor function in context-dependent conditioned fear.
Matsuzaki
Hirokazu
H
Department of Neuropharmacology, Hokkaido University Graduate School of Medicine, North 15, West 7, Sapporo, 060, Japan.
Izumi
Takeshi
T
Horinouchi
Takahiro
T
Boku
Shuken
S
Inoue
Takeshi
T
Yamaguchi
Taku
T
Yoshida
Takayuki
T
Matsumoto
Machiko
M
Togashi
Hiroko
H
Miwa
Soichi
S
Koyama
Tsukasa
T
Yoshioka
Mitsuhiro
M
D017371:8-Hydroxy-2-(di-n-propylamino)tetralin / Q000494:pharmacology; D000367:Age Factors; D000818:Animals; D004195:Disease Models, Animal; D005239:Fear; D046352:Freezing Reaction, Cataleptic; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D011485:Protein Binding; D051381:Rats; D017208:Rats, Wistar; D044282:Receptor, Serotonin, 5-HT1A / Q000378:metabolism*; D058825:Serotonin 5-HT1 Receptor Agonists / Q000494:pharmacology; D013315:Stress, Psychological
D058825:Serotonin 5-HT1 Receptor Agonists; D044282:Receptor, Serotonin, 5-HT1A; D017371:8-Hydroxy-2-(di-n-propylamino)tetralin