Effects of food restriction on peroxisome proliferator-activated receptor-γ and glucocorticoid receptor signaling in adipose tissues of normal rats

Keiko Arai, Tomoko Soga, Hisayuki Ohata, Asuka Otagiri, Tamotsu Shibasaki

Research output: Contribution to journalArticleResearchpeer-review

15 Citations (Scopus)

Abstract

In adipocytes, peroxisome proliferator-activated receptor (PPAR)-γ activates adipocyte differentiation and glucocorticoid (GC) stimulates the expression of PPAR-γ mRNA. The local tissue concentrations of GC, in turn, are modulated by 11β-hydroxy-steroid dehydrogenase type 1 (11β-HSD1). To clarify the change of energy metabolism in condition of reduced energy intake, we investigated whether food restriction alters the adipocyte size and levels of PPAR-γ, GC receptor (GR), and 11β-HSD1 mRNA expression in the white adipose tissues of normal rats. Male Wistar rats weighing 340 g were housed under free feeding or 20% reduction of food intake for 2 or 14 days. We found that 2-day food restriction did not cause any change in the mean size or number of adipocytes in the omentum, while 14-day food restriction decreased the size and increased the number of adipocytes. In addition, the levels of PPAR-γ2, GR, and 11β-HSD1 mRNA expression in the omentum were lower in the food-restricted rats after 2 days, while they did not differ after 14 days. Also, after both 2 and 14 days, plasma concentrations of free fatty acid (FFA) were higher in the food-restricted rats than in control rats. Finally, plasma concentrations of adrenocorticotropin (ACTH) and corticosterone were the same in the both groups after 2 days, although they were higher in the food-restricted rats after 14 days. These results suggest that adipocyte differentiation in the omentum of food-restricted rats is attenuated after 2 days but recovers after 14 days, resulting in an increase in the number of small adipocytes. It is also likely that lipolysis induced during the 14-day period of food restriction decreased the size of adipocytes. Further, food restriction may affect the efficiency of local GC effects by altering GR and 11β-HSD1 mRNA expression. Also, higher levels of plasma GC and recovery of GR and 11β-HSD1 mRNA expression may contribute to the recovery of the levels of PPAR-γ2 mRNA expression in the omentum and result in the recovery of adipocyte differentiation.

Original languageEnglish
Pages (from-to)28-36
Number of pages9
JournalMetabolism: Clinical and Experimental
Volume53
Issue number1
DOIs
Publication statusPublished - Jan 2004
Externally publishedYes

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