OBJECTIVE

To investigate the effect of pioglitazone on visfatin expression.

METHODS

We studied the effect of pioglitazone on visfatin expression in 3T3-L1 adipocytes and serum concentrations and tissue expression of visfatin in normal Sprague-Dawley rats and rats with insulin resistance induced by high-fat diet (HF). Metabolic and anatomical parameters of the rats were also performed.

RESULTS

In 3T3-L1 adipocytes, visfatin expression increased during the differentiation and it was not regulated by pioglitazone. In the rats, 12 weeks of HF feeding induced obesity and increased fast blood glucose (FBG), serum insulin and circulating visfatin. Pioglitazone treatment ameliorated insulin resistance with concomitant reduction in serum visfatin, free fatty acid, and triglyceride (TG) of the rats fed HF. Compared with subcutaneous adipose tissue and muscle, visfatin protein expression was much higher in visceral adipose tissue on both diets (p < 0.05 for all). Visfatin expression decreased in visceral adipose tissue but not subcutaneous adipose tissue or muscle after pioglitazone treatment in HF-fed rats. Visfatin expression in the rats fed chow diet was not affected by pioglitazone. Additionally, we demonstrated that serum visfatin was positively correlated with visceral adipose tissue weight, visfatin in visceral adipose tissue, TG and FBG (p < 0.05 for all).

CONCLUSION

Visfatin is preferentially produced by visceral fat and peroxisome proliferator-activated receptor-gamma agonist ameliorates the development of insulin resistance in HF-fed rats with a major decrease in visfatin expression, the effect of pioglitazone on visfatin in HF-fed rats is dependent on glucose and lipid metabolism in the animals.