Preferential Uptake of Estradiol by the Anterior Hypothalamus of the Rat

Abstract

Adult ovariectomized rats were injected with a small dose of tritium-labeled estradiol and the uptake and retention of radioactivity in various parts of the brain were measured. The anterior hypothalamus and median eminence showed a characteristic pattern of uptake and retention of radioactivity similar to that shown by the uterus and vagina. The radioactivity taken up was extracted and shown to be largely estradiol itself. Other parts of the brain, which did not selectively take up and retain radioactivity, either converted a relatively larger fraction of the estradiol to estrone and other products or took up estrone made elsewhere in the body from the injected estradiol. The anterior hypophysis was also shown in these experiments to take up and retain estradiol and to convert only a small fraction of it to estrone. The selective uptake and retention of estradiol by the anterior hypothalamus and median eminence suggests a means by which the hormone could initiate the sequence of reactions by which it exerts its feedback control of the central nervous system. (Endocrinology80: 567, 1967)