Human granulosa cells in vitro: Influence of GnRH/GnRH-agonist on steroidogenesis and on IVF outcome

Steroidogenic activities of the granu losa cells (GCs) from 84 IVF trials were evaluated with respect to a set of ovari an stimulation regimens. Oestradiol (E2) systhesis of the GCs ill vitro (obtained at oocyte retrieval) was compared to the maximal serum E2 levels of the same patients at induction of ovul ation . Three stimulation regimens were employed: human post-menopausal gonadotrophin (hMG) alone; hMG accompanied by daily doses of a gonadotrophin releasing hormone agonist (GnRH-a); hMG preceeded by a si ngle depot application of the GnRH-a. Plots of E2 synthesis ill vitro against serum E2 levels indicated that the GnRH-a directly inhibited E2 synthesis in the granulosa cell s. This was conllrmed ill "itm by adding the agonist to the culture medium: both progesterone (P) and E2 syntheses were reduced in the presence of GnRH-a. Despite thi s drawback, the success of ill vitro fertili sation (IVF) , as gauged by pregnancies achi eved, was best for the group whi ch received the GnRH-a as a single depot dose during the previous menstrual cycle, prior to the commence of st imulation. This success is attributed to the lower incidence of cancell ations because of premature leuteini sin g hormone (LH) surges which happen sometimes during ovarian stimulati on. The implications of a direct influence of GnR H-a on E2 synthesis need to be further in vestigated.