Department of Obstetrics and Gynaecology, University of Thessalia, Medical School, 41222 Larissa, Greece
Great progress in the ovarian mechanisms that control gonadotrophin
secretion in women has recently been achieved. Estradiol (E
2)
is the main component of the ovarian negative effect on basal
gonadotropin secretion during the normal menstrual cycle. However,
nonsteroidal substances such as inhibins and activins that can
affect follicle-stimulating hormone (FSH) secretion
in vitro may also participate in the control of FSH secretion
in vivo.
Recent evidence has shown that the ovaries also produce another
nonsteroidal substance, named gonadotropin surge-attenuating
factor (GnSAF), that specifically attenuates GnRH-induced LH
secretion and the endogenous LH surge in superovulated women.
It is possible that during the normal menstrual cycle GnSAF
controls the amplitude of the midcycle LH surge by antagonizing
the stimulating effect of E
2 on the pituitary.
