A comparison of the relationships between progestin receptors and oestrogen receptors in neural and non-neural target tissues of the rat during the oestrous cycle.

Similar cyclic changes in the content of nuclear oestrogen receptor occurred in the hypothalamus, cerebral cortex, uterus and pituitary during the oestrous cycle. The relationship of the unoccupied to the total nuclear oestrogen receptor at each phase was similar in all these tissues. However, cyclic changes in the content of the cytosol progestin receptor occurred only in the uterus and pituitary (where they paralleled changes in the nuclear oestrogen receptor), but not in the hypothalamus or cerebral cortex.