Uptake of3H-Estradiol by the Female Rat Brain. An Autoradiographic Study

Abstract

Adult ovariectomized rats were injected iv with tritiated estradiol, and the uptake and retention of radioactivity in the brain were studied autoradiographically. The radiochemical was fixed in brain tissue, in preparation for autoradiography, with osminum tetroxide and formalin. Quantitative measurements of uptake were made by counting reduced grains over cell bodies in various brain structures in the autoradiograms. One-half hr. after injection of a low dose, or 1 1/4 hr. after a higher dose, nerve cells and glial cells throughout the brain concentrated the radiochemical. Uptake in hypo-thalamic, olfactory and limbic structures was about 1 1/2 times as great as uptake in other brain regions. Two hr. after injection of a low dose, uptake was still high in the limbic system and hypothalamus, but had fallen considerably in the olfactory bulb and in nonlimbic structures. Thus, the time course of uptake in cells in the limbic system and hypothalamus resembled that seen in the uterus and vagina, whereas the time course in other brain structures did not.