LEPTIN CONCENTRATIONS IN THE FOLLICULAR PHASE OF SPONTANEOUS CYCLES AND CYCLES SUPEROVULATED WITH FOLLICLE-STIMULATING-HORMONE

It has been reported that oestradiol may play a role in the production of leptin from adipocytes, To investigate this relationship further, nine normally ovulating women were studied during two menstrual cycles , i.e. an untreated spontaneous cycle and a cycle treated with follicl e stimulating hormone (FSH) from cycle day 2 until the day of human ch orionic gonadotrophin (HCG) injection, Serum leptin values on cycle da y 2 did not differ significantly between the spontaneous and the FSH c ycles. In the spontaneous cycles, leptin values declined gradually and significantly up to day 7 and then increased progressively up to the day of luteinizing hormone (LH) surge onset, at which point they achie ved the highest values, In the FSH cycles, serum leptin values increas ed gradually and significantly up to day 6, remaining stable thereafte r, and were in the midfollicular phase significantly higher than in th e spontaneous cycles. Significant positive correlations were found bet ween mean values of leptin and mean values of oestradiol during the se cond half of the follicular phase in the spontaneous cycles and during the first half in the FSH cycles, A significant negative correlation was found between these two parameters in the spontaneous cycles durin g the first half of the follicular phase. Serum leptin levels were sig nificantly higher in the midluteal than in the follicular phase in bot h cycles. These results demonstrate for the first time significant cha nges in leptin values during the follicular phase of the human menstru al cycle and a significant increase during superovulation induction wi th FSH. It is suggested that oestradiol may be involved in the regulat ion of leptin production in women.