The inhibitory effect of serotonin on the spontaneous discharge of suprachiasmatic neurons in hypothalamic slice is mediated by 5-HT(7) receptor.
The effects of serotonin (5-HT) receptor agonists and antagonists on the spontaneous discharge of suprachiasmatic nucleus (SCN) neurons were investigated using rat hypothalamic slice. It was found that: (1) the SCN neurons showed a persistent rhythm in the spontaneous discharge rate, which was higher during the light phase than during the dark phase; (2) the effects of 5-HT on SCN neurons was inhibitory in nature and the sensitivity of SCN neurons to 5-HT during the light phase was lower than that during the dark phase; (3) both 5-HT and 5-HT(1/7) receptor agonist, (+/-)-8-hydroxy-2-(DL-N-propylamino) tetralin hydrobromide, could inhibit the spontaneous discharge of SCN neurons. This inhibitory effect could be blocked by 5-HT(2/7) receptor antagonist ritanserin and putative 5-HT(7) receptor antagonists clozapine, but neither by selective 5-HT(2) receptor antagonist ketanserin, nor by 5-HT(1) receptor antagonist pindolol. It was suggested that the inhibitory effect of 5-HT on the spontaneous discharge of SCN neurons in rat hypothalamic slice is mediated by 5-HT(7) receptor subtype.
Yu
G D
GD
Laboratory of Neurobiology, School of Medicine, Soochow University, Suzhou, People's Republic of China.
Liu
Y L
YL
Jiang
X H
XH
Guo
S Y
SY
Zhang
H Q
HQ
Yin
Q Z
QZ
Hisamitsu
T
T
D000818:Animals; D002940:Circadian Rhythm / Q000502:physiology; D007031:Hypothalamus / Q000187:drug effects / Q000502:physiology; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology; D051381:Rats; D017208:Rats, Wistar; D011985:Receptors, Serotonin / Q000187:drug effects* / Q000502:physiology; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology*; D017366:Serotonin Receptor Agonists / Q000494:pharmacology*; D013493:Suprachiasmatic Nucleus / Q000187:drug effects* / Q000502:physiology
D011985:Receptors, Serotonin; D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; C104425:serotonin 7 receptor; D012701:Serotonin