Secretory pattern of leptin and LH during lactational amenorrhoea in breastfeeding normal and polycystic ovarian syndrome women

Several studies have suggested that leptin modulates hypothalamic-pituitary -gonadal axis function. A synchronicity of LH and leptin pulses has been de scribed in healthy women and in patients with polycystic ovarian syndrome ( PCOS), suggesting that leptin may modulate the episodic secretion of LH. Th e aim of the present investigation was to assess the episodic fluctuations of circulating LH and leptin during lactational amenorrhoea in fully breast feeding normal and PCOS women at 4 and 8 weeks postpartum, in order to esta blish LH-leptin interactions in the reactivation of the gonadal axis during this period. Six lactating PCOS patients and six normal lactating women of similar age and body mass index were studied. During a 12 h period on the 4th and 8th weeks postpartum, blood samples were collected at 10 min interv als for 12 h (22:00-10:00). Serum LH and leptin concentrations were measure d in all samples. For pulse analysis, the cluster algorithm was used. To de tect an interaction between LH and leptin pulses, an analysis of co-pulsati lity was employed. LH concentrations tended to increase in both groups betw een the 4th and 8th weeks postpartum; however, serum leptin concentrations were not modified. Leptin pulse frequencies were similar at the 4th and 8th weeks postpartum, and did not differ between groups. Moreover, leptin puls e frequency was higher than LH pulse frequency in both groups, and in the t wo study periods. There was no synchronicity between LH and leptin pulses, and there were no increments in leptin concentration during the night. The fact that leptin concentrations were not modified and no synchronicity betw een LH and leptin pulses was observed suggests that, during lactational ame norrhoea, circulating leptin is probably not involved as a primary signal i n promoting the reactivation of pulsatile LH secretion.