Abstract
Serotonin (5-HT) modulates the phase adjusting effects of light on the mammalian circadian clock through the activation of presynaptic 5-HT(1B) receptors located on retinal terminals in the suprachiasmatic nucleus (SCN). The current study was conducted to determine whether activation of 5-HT(1B) receptors also alters photic regulation of nocturnal pineal melatonin production. Systemic administration of the 5-HT(1B) receptor agonist TFMPP attenuated the inhibitory effect of light on pineal melatonin synthesis in a dose-related manner with an apparent ED50 value of 0.9 mg/kg. The effect of TFMPP on light-induced melatonin suppression was blocked by the 5-HT1 receptor antagonist, methiothepin, but not by the 5-HT(1A) antagonist, WAY 100,635, consistent with the involvement of 5-HT(1B) receptors. The results are consistent with the interpretation that activation of presynaptic 5-HT(1B) receptors on retinal terminals in the SCN attenuates the effect of light on pineal melatonin production, as well as on circadian phase. Copyright (C) 2000 Elsevier Science B.V.
Original language | English (US) |
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Pages (from-to) | 424-428 |
Number of pages | 5 |
Journal | Brain Research |
Volume | 858 |
Issue number | 2 |
DOIs | |
State | Published - Mar 10 2000 |
Externally published | Yes |
Keywords
- 5-HT(1B) receptor
- Circadian rhythm
- Melatonin
- Pineal
- Retinohypothalamic tract
- Suprachiasmatic nucleus
ASJC Scopus subject areas
- Neuroscience(all)
- Molecular Biology
- Clinical Neurology
- Developmental Biology