Charcoal stripping augments type II oestradiol binding in cytoplasmic fraction of rat hypothalami.

Type II [3H]oestradiol binding was assessed by charcoal method in the low speed cytoplasmic fraction of intact female rat hypothalami. Augmented binding was observed after charcoal pretreatment applied prior to binding assay. On the other hand, loss of low affinity oestradiol binding was demonstrated after addition of protein-free ultrafiltrates of the cytosol from hypothalami or uteri. The presence of a cytosolic inhibitor activity specific for type II oestradiol binding in hypothalami is considered.