Are circulating leptin and luteinizing hormone synchronized in patients with polycystic ovary syndrome?

Animal and human studies suggest that leptin modulates hypothalamic-pituita ry-gonadal axis functions. Leptin may stimulate gonadotrophin-releasing hor mone (GnRH) release from the hypothalamus and luteinizing hormone (LH) and follicle stimulating hormone (FSH) secretion from the pituitary, A synchron icity of LH and leptin pulses has been described in healthy women, suggesti ng that leptin probably also regulates the episodic secretion of LH. In som e pathological conditions, such as polycystic ovarian syndrome (PCOS), LH-l eptin interactions are not known. The aim of the present investigation was to assess the episodic fluctuations of circulating LH and leptin in PCOS pa tients compared to regularly menstruating women. Six PCOS patients and six normal cycling (NC) women of similar age and body mass index (BMI) were stu died, To assess episodic hormone secretion, blood samples were collected at 10-min intervals for 6 h, LH and leptin concentrations were measured in al l samples. For pulse analysis the cluster algorithm was used, To detect an interaction between LH and leptin pulses, an analysis of copulsatility was employed, LH concentrations were significantly higher in the PCOS group in comparison to NC women, however serum leptin concentrations and leptin puls e characteristics for PCOS patients did not differ from NC women. A strong synchronicity between LH and leptin pulses was observed in NC women; 11 coi ncident leptin pulses were counted with a phase shift of 0 min (P = 0.027), 18 pulses with a phase shift of -1 (P = 0.025) and 24 pulses with a phase shift of -2 (P = 0.028). PCOS patients also exhibited a synchronicity betwe en LH and leptin pulses but weaker (only 20 of 39 pulses) and with a phase shift greater than in normal women, leptin pulses preceding LH pulses by 20 min (P = 0.0163), These results demonstrate that circulating leptin and LH are synchronized in normal women and patients with PCOS, The real signific ance of the apparent copulsatility between LH and leptin must be elucidated , as well as the mechanisms that account for the ultradian leptin release.