Recombinant human inhibin A and recombinant human activin A regulate pituitary and ovarian function in the adult female rat

The roles of recombinant human inhibin A (rh-inhibin A) and rh-activin A in regulating the pituitary and ovary of the adult female rat were examined. Serum and pituitary FSH and LH and serum estradiol and progesterone concentrations were evaluated at 1, 2, and 6-12 h after sc hormone administration on metestrus and on proestrus. A second study examined the effect of the hormones 24 h after injection at 1000 h on each day of the cycle. Rh-inhibin A inhibited FSH secretion 60 min after injection on proestrus but did not alter serum FSH concentration on metestrus. FSH remained low for the 12 h examined during the evening of proestrus and on the morning of estrus. Serum LH concentration, pituitary FSH content, and pituitary LH content were not significantly changed under any experimental condition. Rh-inhibin A did not regulate estradiol concentration on metestrus or on proestrus; however, it did cause a rise in serum estradiol in animals treated on metestrus and diestrus and examined 24 h later. This suggest...