Effects of fat tissue-derived hormones and cytokines on leptin gene expression and leptin secretion in differentiating preadipocytes
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AbstractAdipocytes have been shown to release an ever-increasing number of biomediators. However the role of these mediators in adipose tissue development remains unclear. The present study investigated the direct effects of exogenous leptin and other adipose tissue-derived cytokines (TNFoc, IL-I p, IL-6, and TGFP) on preadipocyte differentiation and leptin production in vitro. To determine the role of these agents, rat preadipocytes were induced to differentiate with a hormonal cocktail in the absence or presence of cytokines. Addition of leptin to the hormonal cocktail exerted two significant opposing effects on differentiating preadipocytes, depending on the dose used. TNFa, TGFp and IL-IP exerted significant inhibitory effects on preadipocyte differentiation and leptin production, even in the presence of a stimulatory dose of leptin. IL-6 exerted a significant stimulatory effect on preadipocyte differentiation and leptin production, and enhanced the stimulatory effects of leptin. In summary, the present data suggest that adipose tissue-derived hormones and cytokines may play an important role in regulating adipose tissue development.
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