Aging, pituitary hormones and antioxidant enzyme activities in immune and nonimmune organs of rats

OSCAR A. BROWN; ALEJANDRO D. BOLZAN; MARTHA S. BIANCHI; RODOLFO G. GOYA

Río de Janeiro

Simposio; Primer Simposio Internacional sobre "Immunoneuroendocrine interactions in autoimmune and infectious diseases"; 1994

There is growing evidence that cytokines can modulate the levels of antioxidant enzymes in different tissues. Since the neuroendocrine system Is likely to be also Involved in this modulation, it was of Interest to assess the correlation between circulating levels of pituitary hormones and antioxidant enzyme activities in a number of immune and nonimmune organs in rats. The impact of aging upon this correlation was also evaluated. Seven- and 29-month old Sprague Dawley female rats were used. Serum levels of GH, Prl, TSH, T4, T3, and LH were assessed by RIA. Superoxide dlsmutase (SOD) and catalase (CAT) activities were measured in liver (SOD & CAT), spleen (SOD & CAT), thymus (SOD) and mammary tissue (SOD) by a spectro-photometric method. A marked hyperprolactinemia was the more striking neuroendocrine alteration in our old females (serum PRL in the young and old animals was 9.2 ± 2.3 and 39.9 ± 8.4 ng/ml, respectively). CAT activity, which declined with age in both liver and spleen, showed little correlation with age changes in hormone levels. On the other hand, mammary SOD activity showed a high correlation with Prl levels in both young and old animals (Rs: 0.96 and 0.80, respectively). The correlation between hepatic SOD and TSH, but not T4 or T3, was lower but also significant in both young and old rats (Rs: 0.70 and 0.60, respectively). Thymus but not spleen SOD activity was higher in old rats although this Increase was not correlated with age changes in pituitary hormone levels. Our data suggest that PRL may be a physiologic modulator of mammary SOD levels in rats and that TSH can possibly Influence hepatic SOD activity via a thyroid-independent pathway. Our results also show that, when significant, the correlation between hormone levels and SOD activity deteriorates with age.