Hormonal regulation of the novel adipocytokine visfatin in 3T3-L1 adipocytes

Abstract

Recently, visfatin was characterized as a novel adipocytokine that is upregulated in obesity and exerts insulinmimetic effects in various tissues. To clarify expression and regulation of this adipocytokine, visfatin mRNA was measured by quantitative real-time reverse transcriptionpolymerase chain reaction in 3T3-L1 adipocytes during adipogenesis and after treatment with various hormones known to alter insulin sensitivity. Visfatin expression was about 6-fold higher in 3T3-L1 adipocytes in vitro as compared with epididymal fat in vivo and increased during adipogenic conversion more than 3-fold. Interestingly, 100 nM dexamethasone significantly increased visfatin mRNA by almost 1·5-fold. In contrast, 500 ng/ml growth hormone (GH), 10 ng/ml tumor necrosis factor (TNF) , and 10 µM isoproterenol downregulated visfatin expression by 45%, 36%, and 43% respectively. Insulin did not influence synthesis of this adipocytokine. The effects of dexamethasone, GH, TNF and isoproterenol were time-and dose-dependent. Furthermore, activation of G s -protein-coupled pathways by forskolin and cholera toxin was sufficient to significantly downregulate visfatin mRNA. Taken together, our results show a differential regulation of visfatin mRNA by insulin resistanceinducing hormones, supporting the view that this adipocytokine might be an interesting novel candidate linking core components of the metabolic syndrome such as obesity and insulin resistance.

The release of the adipocytokine visfatin is regulated by glucose and insulin

“…In cultured adipocytes there was little if any impact of glucose on visfatin release when insulin was present and this effect was fully restored by insulin-receptor blockade. This is consistent with findings from other studies demonstrating that insulin alone had no effect on unstimulated 3T3-L1 adipocytes [17]. Although the physiological actions of visfatin are as yet poorly understood, the negative regulation of hyperinsulinaemia may affect circulating visfatin concentrations in patients with diabetes mellitus type 2 or insulin resistance.…”

“…Studies on 3T3-L1 adipocytes have demonstrated that visfatin is regulated by hormones and cytokines influencing glucose homeostasis [17,18]. A surprising finding of our studies was the negative feedback of insulin on glucoseinduced visfatin release.…”

Single and Concurrent Effects of Endurance and Resistance Training on Plasma Visfatin, Insulin, Glucose and Insulin Resistance of Non-Athlete Men with Obesity

“…It is likely that increased growth hormone secretion together with concurrent training has caused visfatin secretion. As Tayebi stated in animal studies, growth hormone causes suppression of visfatin gene expression in adult cells secreting visfatin (38).…”

The effect of glucose intake on Plasma Visfatin response following an aerobic exercise session in male students

“…Although at 90 minutes after exercise the plasma insulin level of the glucose group was higher than that of the water group, but the difference was not significant. It has been shown that insulin does not affect visfatin synthesis in adipocytes, and no significant difference has been observed in the serum visfatin levels of diabetic patients and those who injected insulin or received hypoglycemic agents (23,24). In addition, the effect of insulinsensitizing agents on serum visfatin has not yet been confirmed (25,26).…”