Presence of Estrogen Receptors in the Hen Hypothalamus and Pituitary

In the hen, the preoptic area, medial basal hypothalamus, and anterior lobe of the pituitary showed a greater uptake of [3H]estradiol-17 beta (E2) in vivo than other tissues. This uptake was decreased when unlabeled diethylstilbestrol was injected together with the [3H]E2 or when unlabeled E2 was injected before the [3H]E2 injection. A specific estrogen binding component having properties of a receptor was found in vitro in both soluble and insoluble fractions of these tissues in a hypotonic buffer solution. The administration of E2 in vivo caused a marked decrease in the estrogen receptor binding in the soluble fraction with a concomitant increase in binding in the insoluble fraction; as a result, total binding (sum of the bindings in soluble and insoluble fraction) did not change.