CHARCOAL STRIPPING AUGMENTS TYPE-II ESTRADIOL BINDING IN CYTOPLASMIC FRACTION OF RAT HYPOTHALAMI

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