X-Irradiation of the Rat Ovary Luteinized by Exogenous Gonadotropins: Influence on Steroidogenesis

Abstract

X-irradiation of the immature rat ovary luteinized by exogenous gonadotropins (PMS—HCG) caused destruction of most remaining follicles within 8 days, but the morphological integrity of lutein tissue was maintained. X-irradiated ovaries of seven rats exposed to four daily injections of NIH-LH-S11 (50 μg/rat/day) failed to secrete estrogen in physiologically detectable quantities as indicated by the absence of a uterine growth response. The same regimen of LH caused a significant (p < .01) increase in uterine weight in seven animals with luteinized, sham-irradiated ovaries. Total synthesis of progestin (progesterone and 20α-hydroxypregn-4-en-3-one) in vitro by four tissue pools consisting of X-irradiated ovaries from eight rats was quantitatively comparable to that synthesized by a similar number of sham-irradiated ovarian tissue pools. In this species, lutein tissue remains viable and capable of secreting progestins after exposure to X-irradiation in sufficient dosage to cause destruction of follicles. The inability of the luteinized, X-irradiated ovary to secrete estrogen in response to LH may be attributable to the absence of follicles and/or X-ray-induced destruction of estrogen-producing cells within the lutein tissue.