Regulation of antioxidant enzyme activities in male and female rat macrophages by sex steroids

Human and animal immune functions present sex dimorphism that seems to be m ainly regulated by sex hormones. In the present study, the activities of th e antioxidant enzymes total superoxide dismutase (SOD), catalase (CAT), and glutathione peroxidase (GSH-Px) were measured in intraperitoneal resident macrophages from adult male and female rats. In addition to comparing males and females, we also examined the regulation of these enzyme activities in macrophages by sex steroids. GSH-Px activity did not differ between male a nd female macrophages. However, both total SOD and CAT activities were mark edly higher in females than in males (83 and 180%). Removal of the gonads i n both males and females (comparison between castrated groups) increased th e difference in SOD activity from 83 to 138% and reduced the difference in CAT activity from 180 to 86%. Castration and testosterone administration di d not significantly modify the activities of the antioxidant enzymes in mal e macrophages. Ovariectomy did not affect SOD or GSH-Px activity but marked ly reduced (48%) CAT activity. This latter change was fully reversed by est rogen administration, whereas progesterone had a smaller effect. These resu lts: led us to conclude that differences in the SOD and CAT activities may partially explain some of the differences in immune function reported for m ales and females. Also, estrogen is a potent regulator of CAT in macrophage s and therefore this enzyme activity in macrophages may vary considerably d uring the menstrual cycle.