Cytoplasmic binding of oestradiol-17beta in several brain regions, pituitary and uterus of ferrets ovariectomized while in or out of oestrus.

The reproductive status at the time of ovariectomy had no effect on oestradiol binding. In both groups of ferrets the oestradiol binding capacity of the uterus was approximately 10 times greater than that of the other tissues studied; of these other tissues the highest oestradiol binding capacity was present in the pituitary, followed by hypothalamus, midbrain, amygdala and cerebral cortex. The binding affinity of hypothalamic receptors for oestradiol was the same in ferrets which had been previously ovariectomized while either in oestrus or anoestrus. It is suggested that the occurrence of seasonal oestrus does not depend on changes in the binding capacity or affinity of hypothalamic receptors for oestradiol.