title: Serotonin phase-shifts the mouse suprachiasmatic circadian clock in vitro.
abstract: The mammalian circadian clock in the suprachiasmatic nucleus (SCN) receives multiple afferent signals that could potentially modulate its phase. One input, the serotonin (5-HT) projection from the raphe nuclei, has been extensively investigated in rats and hamsters, yet its role(s) in modulating circadian clock phase remains controversial. To expand our investigation of 5-HT modulation of the SCN clock, we investigated the phase-shifting effects of 5-HT and its agonist, (+)8-hydroxy-2-(di-n-propylamino)tetralin (DPAT), when applied to mouse SCN brain slices. 5-HT induced 2-3 h phase advances when applied during subjective day, while non-significant phase shifts were seen after 5-HT application at other times. These phase shifts were completely blocked by the 5-HT antagonist, metergoline. DPAT also induced phase shifts when applied during mid-subjective day, and this effect appeared dose-dependent. Together, these results demonstrate that the mouse SCN, like that of the rat, is directly sensitive to in vitro phase-resetting by 5-HT.
authors.affiliation: University of Tennessee, Department of Biochemistry and Cellular and Molecular Biology, M407 Walter's Life Sciences Building, Knoxville, TN 37996, USA. rprosser@utk.edu
authors.forename: Rebecca A
authors.initials: RA
authors.lastname: Prosser
mesh_terms: D000818:Animals; D002940:Circadian Rhythm / Q000187:drug effects* / Q000502:physiology; D004305:Dose-Response Relationship, Drug; D066298:In Vitro Techniques; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D012701:Serotonin / Q000494:pharmacology*; D012702:Serotonin Antagonists / Q000494:pharmacology; D017366:Serotonin Receptor Agonists / Q000494:pharmacology; D013493:Suprachiasmatic Nucleus / Q000187:drug effects* / Q000502:physiology
chemical_list: D012702:Serotonin Antagonists; D017366:Serotonin Receptor Agonists; D012701:Serotonin