Effect of somatostatin on circadian rhythms of firing and 2-deoxyglucose uptake in rat suprachiasmatic slices.
In mammals, the suprachiasmatic nucleus (SCN) of the hypothalamus appears to act as a circadian clock. The SCN vasoactive intestinal polypeptide-like immunoreactive neurons, which may act to mediate photic information in the SCN, receive input from neurons immunoreactive for somatostatin (SST). Therefore we investigated the role of SST as a transmitter for entrainment by analyzing the phase-resetting effect of SST on the circadian rhythm of SCN firing activity. Perfusion of SST increased 2-deoxyglucose uptake at circadian time (CT) 18, but not at CT6. A 1-h or 15-min treatment with SST produced phase delays when it was administered at CT13-14 and phase advances at CT22-23. Thus SST-induced phase changes are similar to those for light pulses to animals under constant darkness. The present findings suggest that SST is a transmitter for mediating information of entrainment to circadian clocks within the SCN.
Hamada
T
T
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kyushu University 62, Fukuoka, Japan.
Shibata
S
S
Tsuneyoshi
A
A
Tominaga
K
K
Watanabe
S
S
D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002940:Circadian Rhythm / Q000187:drug effects*; D003847:Deoxyglucose / Q000378:metabolism*; D004553:Electric Conductivity / Q000187:drug effects; D007150:Immunohistochemistry; D066298:In Vitro Techniques; D008564:Membrane Potentials / Q000187:drug effects; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D051381:Rats; D017208:Rats, Wistar; D013004:Somatostatin / Q000494:pharmacology*; D013493:Suprachiasmatic Nucleus / Q000187:drug effects / Q000378:metabolism / Q000502:physiology*; D014660:Vasoactive Intestinal Peptide / Q000032:analysis; D014667:Vasopressins / Q000494:pharmacology
D014667:Vasopressins; D014660:Vasoactive Intestinal Peptide; D013004:Somatostatin; D003847:Deoxyglucose