Leptin is an adipose tissue-derived cytokine plays key roles in the regulation of food intake and energy expenditure. However,
regulatory mechanisms of leptin gene expression are not fully elucidated in ruminants that utilize short-chain fatty acids (SCFA),
known as volatile fatty acids, as principal energy sources. In this study, we determined effects of SCFA and long-chain fatty acids
(LCFA) on leptin expression in bovine adipocytes. Bovine stromal vascular cells isolated from subcutaneous adipose tissue of
Holstein cows were cultured to confluence and treated sequentially with dexamethasone and isobutylmethylxanthine for 2 days and
insulin and troglitazone for 12 days to achieve full differentiation to adipocytes. The cells started to accumulate lipids 4 days after
the onset of treatment, with increased mRNA expression of leptin, as well as aP2, adiponectin, and PPAR-_. Removal of fetal calf
serum and reduction of glucose in the culture medium of differentiated adipocytes decreased leptin mRNA expression. Subsequent
addition of acetate, butyrate, or propionate dose-dependently restored and rather increased leptin expression, while addition of LCFA
suppressed it. The stimulatory effect of acetate was abolished by prior treatment of the cells with pertussis toxin and by addition
of LCFA. Furthermore, cows fasted for 48 h and fed thereafter, elaborate reduced and increased plasma leptin levels, respectively.
Thus, these results suggest that plasma leptin levels in cows are inversely controlled at the transcription level by VFA and LCFA,
and that the effects of SCFA possibly act through a G protein-coupled receptor for SCFA.
© 2006 Elsevier Inc. All rights reserved.
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