PUTATIVE ESTROGEN AND GLUCOCORTICOID RECEPTORS IN THE LIMBIC BRAIN

Abstract

The brain is a target tissue for both estrogens and adrenal steroids. These hormones alter both neuroendocrine activity and behavior. Putative soluble (cytosol) and cell nuclear receptor sites are concentrated in anterior pituitary and in limbic regions of the brain: hypothalamus, preoptic region, and amygdala for estradiol, and hippocampus, septum, and amygdala for corticosterone. Recent experiments will be summarized dealing with the following aspects of our work: (1) the postnatal ontogeny of the estradiol-binding system in the limbic brain of the female rat and the temporal relationship of its development to another estradiol-binding protein, probably identical to the α-fetoprotein, which gradually disappears after birth; (2) effects of estradiol on activities of enzymes in pituitary and in brain regions which contain the putative receptors, which effects may relate to the function of the receptor sites; and (3) properties of the putative brain glucocorticoid receptors with particular emphasis on their binding of corticosterone, dexamethasone, and progesterone. Glucocorticoid receptor sites have been studied both in vivo and in vitro using cytosols and tissue slices, thus allowing us to study the cellular mechanism of binding and the extent of receptor occupation by the physiological range of endogenous corticosterone.