Endocrine Abstracts

Leptin is a circulating hormone produced primarily by the adipose tissue, which controls food intake and energy homeostasis. Important peripheral actions of leptin involve inhibition of insulin biosynthesis and secretion in pancreatic ß-cells. In turn, insulin stimulates leptin secretion from adipose tissue, establishing a hormonal regulatory feedback loop: ‘adipo-insular axis’. The aim of our study was to determine the interrelations between leptin, insulin/insulin resistance and lipid profile in pre- and postmenopausal women. We investigated 146 postmenopausal white women, aged between 42 and 78 years and in adition 45 premenopausal white women aged between 22 and 51 years. In both groups we measured plasma levels of leptin, insulin, fasting glucose, glicemia at two hours after glucose load, total cholesterol, HDL- and LDL- cholesterol and triglycerides. The index of insulin resistance was calculated with HOMA formula [(fasting insulin μUI/mL × fasting glicaemia mg/dl)/405] and body composition was performed by a Body Composition Analyzer TBF 310 GS (Tanita Corporation) measuring Body Mass Index (kg/sqm) – BMI, Fat%, Fat Mass (Kg) – FM, and Fat Free Mass (Kg) – FFM. Statistical analysis performed was: linear regression analysis (correlation between parameters) and paired t-test for differences among groups. We found statistically significant positive correlations between leptin and fat mass, as well as waist circumference in both groups. Our results further suggest that in addition to adiposity, the hyperinsulinemia and lipid profile modulate leptin levels in pre- and postmenopausal women. Also, plasma leptin levels, mainly in premenopausal women, could be a predictor for the development of the insulin resistance syndrome and the risk for cardiovascular diseases.