Serotonergic phase shifts of the mammalian circadian clock: effects of tetrodotoxin and high Mg2+.
The mammalian circadian clock in the suprachiasmatic nuclei (SCN) can be phase-shifted in vitro by the serotonin agonist quipazine. Here we show that quipazine resets the SCN clock in the presence of tetrodotoxin or 10 mM Mg2+, treatments that block Na+ action potentials and Ca2+ channels, respectively. These results support the hypothesis that quipazine resets the clock by stimulating receptors located on clock elements rather than on cells afferent to the clock.
Prosser
R A
RA
Department of Biological Sciences, Stanford University, CA 94305.
Heller
H C
HC
Miller
J D
JD
D000818:Animals; D001921:Brain / Q000187:drug effects / Q000502:physiology*; D002940:Circadian Rhythm / Q000187:drug effects*; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology*; D008297:Male; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D015221:Potassium Channels / Q000187:drug effects / Q000502:physiology; D011814:Quipazine / Q000494:pharmacology*; D051381:Rats; D011919:Rats, Inbred Strains; D012701:Serotonin / Q000502:physiology; D012964:Sodium / Q000494:pharmacology; D013779:Tetrodotoxin / Q000494:pharmacology*
D015221:Potassium Channels; D012701:Serotonin; D013779:Tetrodotoxin; D011814:Quipazine; D012964:Sodium; D008274:Magnesium