INTERRELATIONSHIP BETWEEN LEPTIN, TSH AND FREE FATTY ACIDS DURING FASTING IN WOMEN WITH POLYCYSTIC OVARY SYNDROME: DIURNAL COSYNOR ANALYSIS
D Macut1, D Micic1, G Cvijovic1, M Sumarac1, A Kendereski1, M Zarkovic1, J Bjekic2 & FF Casanueva3
It is supposed a simillar dirnal change of TSH, free fatty acids (FFA) and leptin in humans. Hypothalamic-pituitary-thyroid axis (HPT) is suppressed during food deprivation while there is an elevation of FFA further influencing glucose metabolism. The aim of our study was to investigate whether leptin can act as a metabolic signal linking the adipose tissue metabolism and the HPT. We studied 13 women with polycystic ovary disease-PCOS (mean age: 26.6±1.83 years; BMI: 34.0±1.08 kg/m2) during 72-hours of fasting (between day 0 and day 4). Serum leptin (Linco Research, St.Charles, MI; ng/ml), TSH (Delfia, Wallac, Finland; mU/l) and FFA (colorimetric method, RANDOX, UK; mmol/l) were determined as pooled value (sampling every 10 min for 30 min) at 0800, 1200, 1600, 2000, 2400 and 0400 h of the day 0 and day 4. MESOR and amplitude of leptin, TSH and FFA were determined by cosinor analysis from the individual data. Data are presented as mean ± SEM. Paired sampled t-test and Pearson correlation coeficient were used for statistical analysis. Following results for day 0 and day 4 were obtained for leptin: MESOR: 25.12±2.77 vs. 13.12±2.15, p<0.01; amplitude: 6.91±3.10 vs. 3.03±1.12, p>0.05; for TSH: MESOR: 1.5±0.36 vs. 1.05±0.27, p<0.01; amplitude: 0.67±0.17 vs. 0.35±0.10, p<0.05; and for FFA: MESOR: 0.48±0.07 vs. 1.10±0.06, p<0.01; amplitude: 0.10±0.01 vs. 0.08±0.02, p>0.05. Significant correlation was obtained between day 0 MESOR leptin and FFA (r= -0.703, p<0.05), and day 4 MESOR FFA and amplitude TSH (r= 0.629, p<0.05). In conclusion, MESOR values were decreased in leptin, TSH and FFA while only TSH amplitude significantly decreased during fasting. Changes in serum leptin levels occur in a parallel manner with TSH and FFA during fasting indicating their integrated role in energy expenditure.