Effect of somatostatin on circadian rhythms of firing and 2-deoxyglucose uptake in rat suprachiasmatic slices

• Published in: The American journal of physiology Vol. 265; no. 5 Pt 2; pp. R1199 - R1204
• Main Authors: Hamada, T, Shibata, S, Tsuneyoshi, A, Tominaga, K, Watanabe, S
• Format: Journal Article
• Language: English
• Published: United States 01-11-1993
• Subjects: Animals; Biological Transport - drug effects; Circadian Rhythm - drug effects; Deoxyglucose - metabolism; Electric Conductivity - drug effects; Immunohistochemistry; In Vitro Techniques; Membrane Potentials - drug effects; Neurons - drug effects; Neurons - physiology; Rats; Rats, Wistar; Somatostatin - pharmacology; Suprachiasmatic Nucleus - drug effects; Suprachiasmatic Nucleus - metabolism; Suprachiasmatic Nucleus - physiology; Vasoactive Intestinal Peptide - analysis; Vasopressins - pharmacology
• ISSN: 0002-9513
• DOI: 10.1152/ajpregu.1993.265.5.R1199

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.