IMR Press / FBE / Volume 2 / Issue 4 / DOI: 10.2741/E195

Frontiers in Bioscience-Elite (FBE) is published by IMR Press from Volume 13 Issue 2 (2021). Previous articles were published by another publisher on a subscription basis, and they are hosted by IMR Press on imrpress.com as a courtesy and upon agreement with Frontiers in Bioscience.

Open Access Article
Contribution of central SGK-1 to the acute phase responses of mice to social isolation
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1 Department of Lifestyle Medicine, Biomedical Engineering Center, Tohoku University and Metabolic Care Clinic, Tohoku University Hospital, 1-1 Seiryou-machi, Aoba-ku, Sendai, Miyagi 980-8574, Japan
Academic Editor:Katsunori Nonogaki
Front. Biosci. (Elite Ed) 2010, 2(4), 1355–1361; https://doi.org/10.2741/E195
Published: 1 June 2010
(This article belongs to the Special Issue Neural network and energy homeostasis)
Abstract

Ghrelin is a hormone produced mainly by P/D1 cells which line the fundus of the stomach and epsilon cells of the pancreas that stimulate hunger. Ghrelin exists in an endocrinologicaly inactive (des-acyl ghrelin) and active (n-octanoyl-modified ghrelin) forms. The serum- and glucocorticoid-inducible kinase 1 (SGK-1) is a member of the AGC family of serine/threonine protein kinase. In this study, mice were isolated individually or in groups, and deprived from food supply for a period of 24-h. Despite decreases in plasma corticosterone levels and no changes in plasma des-acyl ghrelin, and the expression of hypothalamic neuropeptide Y and proopiomelanocortin, plasma active ghrelin levels and the expression of hypothalamic SGK-1 increased in the acute-isolated mice. Injection of SGK-1 small interfering RNA (siRNA) oligonucleotide into the third cerebral ventricle suppressed the acute social isolation-induced decreases in body weight and increases in plasma active ghrelin levels. Pretreatment with phentolamine (alpha-adrenergic receptor antagonist) but not alprenolol (beta-adrenergic receptor antagonist), partially but significantly suppressed the decreases in body weight induced by acute isolation stress. These finding suggest that isolation stress is a novel inducer of hypothalamic SGK-1 expression. SGK-1 might contribute to the isolation stress-induced body weight reductions and increases in plasma active ghrelin levels via, at least partly, altered central autonomic outflow in mice.

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