SUPEROXIDE-DISMUTASE, CATALASE AND GLUTATHIONE-PEROXIDASE ACTIVITIES IN THE LYMPHOID ORGANS OF DIABETIC RATS

The effect of alloxan-induced diabetes on CuZn- and Mn-superoxide dism utase (SOD), catalase and glutathione peroxidase (GPX) activities, as well as the content of thiobarbituric acid reactive substances (TBARs) were examined in rat lymphoid organs (mesenteric lymph nodes (MLN), t hymus and spleen) and, for comparison, red and white muscle fibres. Th e capacity for generation of reduced equivalents was also evaluated by measuring the activities of glucose-6-phosphate dehydrogenase (pentos e-phosphate path way - cytosol) and citrate synthase (Krebs cycle - mi tochondria). Diabetes raised the capacity for the generation of reduci ng equivalents in the lymphoid organs: in the mitochondria of the thym us and spleen and in the cytosol of the mesenteric lymph nodes and thy mus. In muscles, diabetes reduced CuZn-SOD activity in soleus and rais ed the activity in gastrocnemius, and depressed the activities of cata lase in soleus and of glutathione peroxidase in both soleus and gastro cnemius. In relation to the lymphoid organs, the spleen showed a decre ase in the antioxidant enzyme activities (except for glutathione perox idase), whereas the thymus showed an increased level (except for Mn-SO D), and the MLN presented a reduction in Mn-SOD and catalase activitie s and an increase in GPX activity caused by diabetes. The content of T BARs in the tissues followed the changes in GPX activity inversely: i. e. a decrease in the lymphoid organs (except in the spleen) and an inc rease in the muscles of diabetic rats compared with the control group. All these changes found in diabetic rats were reversed by insulin tre atment and were not modified by the normalization of glycaemia.