Glutathione peroxidase in blood of diabetic and nondiabetic BB rats

The activity of glutathione peroxidase (GPX), an antioxidant selenoenzyme (EC.1.11.1.9.), was investigated in blood of BB rats developing spontaneous diabetes mellitus. The activity of the enzyme was significantly higher in the 4th and 5th inbred generation (G(4-5)) of BB rats as compared with their counterparts of lower degree of inbreeding (G(1-3)). Overt diabetes (actual blood glucose over 10 mM) appeared only in 8 out of 25 G(5) animals but oral and intravenous glucose tolerance tests revealed a gradual worsening of glucose metabolism already in rats with lower degree of inbreeding. No difference in GPX activity was found between diabetic and nondiabetic members of G(5) group. In the whole group of 69 rats positive correlation was found between the blood GPX activity and the age, weight and actual blood glucose value of the rats and negative correlation between GPX and the P/F value (ratio of peak blood glucose after intravenous tolerance test and fasting blood glucose). In the diabetic animals the enzyme activity showed inverse relationships with every measured or calculated parameter of glucose metabolism. Our findings indicate a relationship between age and blood GPX activity of BB rats and suggest the possibility of deleterious effect of elevated blood glucose level on the blood GPX activity after development of overt diabetes.