Effect of 17-beta Estradiol on Adipocyte Lipin-1 Expression in OLETF Rat

ABSTRACT

BACKGROUND: 17 beta-estradiol is known to play an important role in glucose homeostasis. Lipin-1 is a nuclear protein that is essential in adipocyte differentiation and it is considered to play a role in ectopic fat deposition and the redistribution of fat. The aim of this study was to evaluate the effect of 17 beta-estradiol on the lipin-1 expression in the adipocytes of OLETF rats, which is an animal model of diabetes. METHODS: The OLETF rats were divided into 3 groups, 1) the sham-operation group (SHAM) 2) the castrated group (CAST) and 2) the castrated and estradiol treatment group (EST), and all the rats were at 6 weeks of age. LETO rats were used as a control group (LETO). 0.1 mg of estradiol valerate was injected subcutaneously every 4 weeks in the rats of the EST group. The visceral and subcutaneous tissues were isolated to evaluate the lipin-1 protein expression. The lipin-1 expression was measured in human visceral and subcutaneous preadipocytes. RESULTS: Less body weight gain was observed in the EST group compared with that of the SHAM group. In addition, improvement in the glucose tolerance was observed in the EST group. The lipin-1 expression in visceral fat was decreased in the SHAM and CAST groups, but it was but recovered in the EST group. The lipin-1 expression in the subcutaneous fat was decreased in the SHAM, CAST, and EST groups. CONCLUSION: Long term estradiol treatment in OLETF rats reduces the body weight gain and improves the glucose tolerance. Estradiol enhances the lipin-1 protein expression in the visceral adipocytes, but not in the subcutaneous adipocytes.