Changes of circulating leptin levels during normal menstrual cycle: relationship to estradiol and progesterone.

A possible role of ovarian steroids on the modulation of leptin production has recently been suggested. To investigate the relationship between leptin and ovarian steroids during the normal menstrual cycle, twenty-three healthy, normal-weight women were enrolled in the study. Blood was collected into chilled EDTA tubes on cycle days (D) 3, 7, 10, preovulatory (D13-15), midluteal (D 21-23) and late luteal (D 25-27) phases. Plasma leptin, estradiol (E2), progesterone (P), luteinizing hormone (LH) and follicle-stimulating hormone (FSH) were measured by RIA. Leptin levels showed no significant changes throughout the follicular (D7 and D10), preovulatory (8.6 +/- 0.5 ng/mL), midluteal (8.9 +/- 0.6 ng/mL) and late luteal (7.7 +/- 0.4 ng/mL) phases, as compared with those of D3 (7.4 +/- 0.5 ng/mL) level. There was no positive correlation between leptin and E2 levels in D 3 and D 7 (r = 0.14, P > 0.05) or in D 10 and preovulatory day (r = 0.25, P > 0.05). Also, no positive correlation between leptin and E2 (r = 0.12, P > 0.05) or leptin and P (r = 0.17, P > 0.05) levels were observed in the mid- and late luteal phases. These data clearly indicate that physiological alterations of circulating E2 and P concentrations have no significant influence on the leptin changes during normal menstrual cycle.