Serum leptin and leptin receptor isoforms in omental adipose tissue of nondiabetic women undergoing gynecologic surgery for benign disease.

BACKGROUND AND PURPOSE: Leptin is important in the regulation of fat mass and body weight. Adipose tissue not only secretes leptin but also serves as a site of action for leptin. This study was designed to examine the relationships among tissue expression of leptin receptors, serum leptin, and body mass index. METHODS: Omental adipose tissue and fasting blood samples were obtained from 57 nondiabetic women who underwent surgery for either myoma of the uterus or ovarian cyst. Tissue RNA was extracted using Trizol reagent and serum leptin concentrations were determined with commercial kits. The leptin receptor isoforms in tissues were quantified using real-time Taqman technology. RESULTS: Three leptin receptor isoforms, Ob-Rb, HuB219.1, and HuB219.3, were found in human omental adipose tissue. The amounts of HuB219.1 and HuB219.3 mRNA relative to that of Ob-Rb were 1314.2 and 16.7, respectively. Higher body mass index was significantly correlated with an increase in serum leptin concentration and a decrease in leptin receptor HuB219.1 isoform in omental fat, even after adjustment for age and menopausal status. There was no direct association between serum leptin concentration and tissue HuB219.1 mRNA level. CONCLUSIONS: HuB219.1 is the major isoform of leptin receptor expressed in human omental adipose tissue. Our findings suggest that the shorter leptin receptor isoforms in human omental adipose tissue might play an important role in body weight control. Further studies on the inter-relationship between leptin concentrations and multiple leptin receptor isoforms are needed to elucidate the exact mechanism of obesity.