Document Type
Article
Publication Date
3-14-2007
Publication Title
Journal of Neuroscience
Abstract
The orexigenic peptide ghrelin stimulates both food intake and growth hormone release and is synthesized in the stomach and in hypothalamic areas involved in feeding control. The suprachiasmatic nuclei of the hypothalamus (SCN) control most circadian rhythms, although there is evidence that some oscillators, such as food-entrainable oscillators, can drive activity rhythms even after SCN ablation. Ghrelin levels exhibit a circadian rhythm and closely follow feeding schedules, making this peptide a putative candidate for food-related entraining signals. We examined the response of the SCN to ghrelin treatments in vitro, by means of electrophysiological and bioluminescence recordings, and in vivo, by assessing effects on the phase of locomotor activity rhythms. Ghrelin applied at circadian time 6 in vitro to cultured SCN slices induced an ∼3 h phase advance. In addition, ghrelin phase advanced the rhythm of PER2::LUC (Period2::Luciferase) expression in cultured SCN explants from mPer2Luc transgenic mice. In vivo, intraperitoneal administration of ghrelin or a synthetic analog, growth hormone-releasing protein-6 (GHRP-6), to ad libitum fed animals failed to alter circadian phase. When injected after 30 h of food deprivation, GHRP-6 induced a phase advance compared with saline-injected animals. These results indicate that ghrelin may play a role in the circadian system by exerting a direct action on the SCN and that the system as a whole may become sensitive to ghrelin and other feeding-related neuropeptides under conditions of food restriction.
Keywords
Bioluminescence, Electrophysiology, Food entrainment, Ghrelin, GHRP-6, Phase shift
Volume
27
Issue
11
First Page
2890
Last Page
2895
DOI
10.1523/JNEUROSCI.3913-06.2007
ISSN
02706474
Rights
© 2007 Society for Neuroscience.
Recommended Citation
Yannielli, Paola C.; Molyneux, Penny C.; Harrington, Mary E.; and Golombek, Diego A., "Ghrelin Effects on the Circadian System of Mice" (2007). Psychology: Faculty Publications, Smith College, Northampton, MA.
https://scholarworks.smith.edu/psy_facpubs/101
Comments
Archived as published. Open access article.