Effects of Ovariectomy and Estrogen Replacement Therapy on Visceral Adipose Tissue and Serum Adiponectin Levels in Rats

Abstract

Excess visceral adipose tissue accumulation after menopause is closely associated with decreased insulin sensitivity and adiponectin levels. The purpose of this study was to determine the effect of ovariectomy and estrogen replacement on visceral fat and serum adiponectin levels in ovariectomized (OVX) rats. Forty 11-week-old female Wistar rats were divided into the four following groups (n = 10 rats per group): sham-operated control (SHAM); sedentary OVX (OVX-SED); OVX with estrogen replacement (OVX-ER); and OVX with sesame oil treatment (OVX-C). Rats in OVX-ER and OVX-C groups received 17β-estradiol valerate (30 µg/kg, subcutaneously) and sesame oil as vehicle, five days a week, respectively. All animals were sacrificed after eight weeks of intervention. Ovariectomy after eight weeks increased body weight and visceral fat (P < 0.05) in OVX-SED and OVX-C groups compared with SHAM rats with no change in plasma adiponectin levels. Estrogen replacement in OVX animals decreased body weight (13.4%, P < 0.05) and visceral fat (10.4%). Although they were not statistically significant, adiponectin, insulin sensitivity and lipid profile of OVX rats were ameliorated with estrogen treatment. We conclude that ovarian hormone withdrawal leads to higher body weight and visceral adipose tissue in rats, but surprisingly does not change adiponectin levels. Although a substantial decrease in body weight was achieved by estrogen replacement therapy in OVX animals, the beneficial metabolic effects of weight loss seems to be only mechanical, having a tendency to improve insulin sensitivity without elevating adiponectin production.