Relationship between pituitary hormones, antioxidant enzymes, and histopathological changes in the mammary gland of senescent rats

In order to assess the possible involvement of endocrine factors and antioxidant enzymes (AOE) in the mammary pathology typically observed in old female rats, we undertook to determine the relationship between pituitary hormones, AOE activity, and histopathological changes in the mammary gland of senescent rats carrying neoplastic and nonneoplastic mammary pathologies. Serum levels of several pituitary hormones were determined by RIA in young (five months) and senescent (33 months) Sprague-Dawley female rats. The activity of catalase (CAT) and superoxide dismutase (SOD) in mammary tissue from the senescent animals was also determined. Senescent rats showed higher levels of prolactin (PRL) (p < 0.01), thyroid-stimulating hormone (TSH) (p < 0.05) and follicle-stimulating hormone (FSH) (p < 0.01) than their young counterparts. In senescent females the main histopathological findings at mammary level were a marked hyperplasia and the presence of fibroadenomas. In this group there was a positive correlation between serum levels of PRL and the activity of mammary SOD (p < 0.05). There was also a positive correlation between serum levels of FSH and the activity of mammary CAT (p < 0.001). Young females, rendered moderately hyperprolactinemic by means of anterior pituitary grafts, showed clear proliferative changes in their mammary glands. Senescent rats carrying fibroadenomas were less hyperprolactinemic than those with mammary hyperplasia (p < 0.05). Our results provide additional support to the idea that PRL may be a physiological modulator of mammary SOD activity and suggest that FSH can possibly influence the activity of CAT in mammary gland. They also suggest that tumorigenesis but not hyperplasia in rat mammary gland may be associated with low mammary SOD and CAT activities.