Influence of oestradiol and progesterone on pulsatile LH secretion in postmenopausal women

Pulsatile LH secretion was studied in six healthy postmenopausal women. Blood samples were obtained every 10 min during an 8-h saline infusion performed before and during the administration of transdermal oestradiol alone (E2; 50 μg/day) and in combination with vaginal progesterone (P; 100 mg twice daily). Plasma E2 and P levels reached values similar to those found in the early follicular phase and in the luteal phase of the menstrual cycle, respectively. The mean plasma LH levels significantly decreased (P < 0.01) during trans-dermal E2 with and without vaginal P. A significant increase in the frequency (P < 0.025) and the amplitude (P <0.05) of LH pulses was observed during transdermal E2. The administration of vaginal P to oestrongenized women significantly blunted the frequency (P < 0.05) and enhanced the amplitude (P