Effect of estrogen and corticosterone on the lymphoid system in neonatal mice

Abstract

Neonatal female NMRI mice were injected with varying doses of estradiol-17β (E 2), diethylstilbestrol (DES), or corticosterone (CC). All three substances reduced the body weight and the weight of thymus and spleen. On a dose level, DES was more potent than E 2 or CC. DES treatment resulted in pronounced degeneration in thymus cortex, reduced incorporation of [ 3H]thymidine in thymus and spleen, reduced mitotic rate in thymus, and reduced number of leukocytes in peripheral blood with a decreased percentage of mononuclear cells. Nine-week-old animals, injected with DES neonatally, had persistent changes in their peripheral leukocyte population. Cytosol fraction of thymus and spleen from 4- to 5-day-old females contained a DES and E 2-binding macromolecule with a sedimentation coefficient of approximately 4.5S and binding characteristics similar to α-fetoprotein. Autoradiograms of thymus after an [ 3H]DES injection did not show any labeling of thymocytes. The concentration of radioactivity in thymus and spleen after a single [ 3H]DES injection was very low and constant from 10 min to 4 hr after the injection, while a pronounced radioactivity occurred in uterus and skeletal muscle. A model is discussed for the estrogen effect on the lymphoid tissue in neonatal mice. The results underline the importance of studying the immune system in offspring of women treated with DES during pregnancy.