ENDOCRINE AGING IN CBA MICE - CHARACTERIZATION OF UTERINE CYTOSOLIC AND NUCLEAR SEX STEROID-RECEPTORS

Alterations with age in sex steroid hormone/receptor interaction were examined in the uteri of CBA mice. The mean affinity for estrogens and progesterone observed in uterine cytosols and nuclei of old (16-18 mo.) mice were no different than those observed in young (4-8 mo.) animals. Whereas the total number of unoccupied estrogenic receptor sites in old uteri did not differ significantly from that observed in uteri of young mice, aging was accompanied by a 3-fold and significant decrease in mean nuclear binding sites when standardized as mg of DNA (P < 0.05). Aging uteri showed a 3-fold and significant decrease in the total number of uterine progesterone receptor concentration (P < 0.05) which was manifested by a decrease of progesterone binding sites in the cytosol and the nucleus. Aging CBA mice present a profile of altered hormone-receptor interraction which is only partly dependent on ovarian steroids.