Role of 5-HT1B receptors in entrainment disorder of Otsuka Long Evans Tokushima fatty (OLETF) rats.
The role of 5-HT1A and 5-HT1B receptors in entrainment function was studied in Otsuka Long Evans Tokushima fatty (OLETF) rats and control Long Evans Tokushima Otsuka (LETO) rats. Light-induced (100 lux, 30 min) Fos expression in the suprachiasmatic nucleus was studied. Light-induced Fos expression was significantly decreased in OLETF rats compared to that in LETO rats. The decrease of light-induced Fos expression in OLETF rats was significantly reversed by pretreatment with the 5-HT1B receptor antagonist, isamoltan (3 mg/kg, i.p.). Simultaneous administration of CGS12066B (5 mg/kg, i.p.), a 5-HT1B agonist, blocked the reversal effect of isamoltan on Fos expression. Fos expression was not changed in LETO rats by pretreatment with isamoltan (3 mg/kg, i.p.). The Fos expression in LETO and OLETF rats was significantly decreased by pretreatment with the 5-HT1A antagonist, WAY-100,635. Phase shifts in locomotor activity paralleled the Fos expression. Light-induced phase shifts of locomotor activity in OLETF rats were significantly smaller than those in LETO rats. The phase shifts were significantly increased by isamoltan (3 mg/kg, i.p.) in OLETF rats. These results suggest that 5-HT1B receptors are involved in the reduced entrainment function of OLETF rats.
Shimazoe
T
T
Department of Pharmacology, Graduate School of Pharmaceutical Sciences, Kyushu University, 812-8582, Fukuoka, Japan. shimazoe@phar.kyushu-u.ac.jp
Nakamura
S
S
Kobayashi
K
K
Watanabe
S
S
Miyasaka
K
K
Kono
A
A
Funakoshi
A
A
D000818:Animals; D021081:Chronobiology Disorders / Q000235:genetics / Q000503:physiopathology; D002940:Circadian Rhythm / Q000187:drug effects / Q000502:physiology*; D003624:Darkness; D016762:Genes, fos / Q000187:drug effects / Q000235:genetics / Q000502:physiology; D008027:Light; D008297:Male; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D020334:Rats, Inbred OLETF; D044302:Receptor, Serotonin, 5-HT1B / Q000235:genetics / Q000502:physiology*; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists / Q000494:pharmacology; D013045:Species Specificity; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000502:physiology*
D044302:Receptor, Serotonin, 5-HT1B; D058829:Serotonin 5-HT1 Receptor Antagonists; D012702:Serotonin Antagonists