Translator Disclaimer
25 August 2008 Absence of Effects of Short-Term Fasting on Plasma Ghrelin and Brain Expression of Ghrelin Receptors in the Tilapia, Oreochromis mossambicus
Author Affiliations +
Abstract

Ghrelin is an important endocrine peptide that links the gastrointestinal system and brain in the regulation of food intake and energy expenditure. In human, rat, and goldfish plasma levels of ghrelin and GH are elevated in fasted animals, suggesting that ghrelin is an orexigenic signal and a driving force behind the elevated plasma levels of GH during fasting. Ghrelin’s orexigenic action is mediated by the ghrelin receptor (GHS-R1a and GHS-R1b) which is localized on neuropeptide Y (NPY) neurons in the brain. Studies were undertaken to investigate the effect of short-term fasting on plasma ghrelin and brain expression of GHS-R1a, GHS-R1b, and NPY in the tilapia. Fasting for 7 days had no effect on plasma ghrelin concentrations, whereas significant increases in plasma levels of GH were observed on day 3. Fasting significantly reduced plasma levels of IGF-I on days 3 and 7, and of glucose on days 3, 5, and 7. Brain expression of ghrelin and GHS-R1b were significantly elevated in fasted fish on day 3, but were significantly reduced on day 5. This reduction was likely due to a significant increase in the expression in the fed controls on day 5 compared to day 0. No change was detected in the expression of GHS-R1a or NPY in the brain. These results indicate that ghrelin is not acting as a hunger signal in short-term fasted tilapia and is not responsible for the elevated levels of plasma GH.

Larry G. Riley, Bradley K. Fox, Jason P. Breves, Hiroyuki Kaiya, Casey P. Dorough, Tetsuya Hirano, and E. Gordon Grau "Absence of Effects of Short-Term Fasting on Plasma Ghrelin and Brain Expression of Ghrelin Receptors in the Tilapia, Oreochromis mossambicus," Zoological Science 25(8), 821-827, (25 August 2008). https://doi.org/10.2108/zsj.25.821
Received: 5 March 2008; Accepted: 20 May 2008; Published: 25 August 2008
JOURNAL ARTICLE
7 PAGES


SHARE
ARTICLE IMPACT
RIGHTS & PERMISSIONS
Get copyright permission
Back to Top