Effects of a gonadotropin-releasing hormone agonist on progesterone formation in cultured human granulosa cells

Human granulosa cells from follicles of natural cycles (13 women) in mid- or late follicular phase were cultured in modified Medium-199. Human luteinizing hormone (100 micrograms/l), follicle-stimulating hormone (100 micrograms/l) and gonadotropin-releasing hormone agonist (GnRHa) (10(-12) to 10(-6) mol/l) alone or in combination were added to the culture medium. Medium content of progesterone was analysed. In granulosa cells obtained in the mid-follicular phase, the basal progesterone formation averaged 0.5 pg.cell-1.(48 h)-1. FSH caused a 3-fold stimulation. GnRHa (10(-6) mol/l) had a variable influence on the basal progesterone formation, whereas it consistently inhibited (40-50%) the FSH response. In granulosa cells from late follicular phase basal progesterone formation averaged 5 pg.cell-1.(48 h)-1 and was stimulated 3- to 6-fold by LH. GnRHa (10(-6) mol/l) stimulated the basal progesterone formation and caused a tended to potentiate the LH response on progesterone formation. It is concluded that GnRHa at relatively high concentrations exerts direct effects on gonadotropin-stimulated progesterone formation of human granulosa cells and that these effects are different (inhibitory or stimulatory) dependent on the degree of follicular maturation, and/or type of gonadotropin used.