The absence of cardiomyopathy is accompanied by increased activities of CAT, MnSOD and GST in long-term diabetes in rats

The activities of the antioxidant enzymes superoxide dismutase (SOD), catalase (CAT) and glutathione S-transferase (GST), the incidence of DNA damage, the activation of poly (ADP-ribose) polymerase-1 (PARP-1), a marker of DNA repair, and connective tissue growth factor (CTGF), a marker of tissue fibrosis, were examined in the hearts of rats for 16 weeks after diabetes induction by streptozotocin (STZ) administration. A 150% increase in CAT activity was detected at the end of the 2nd week post-STZ administration, and CAT activity remained 80% above the control level throughout 16 weeks. While total SOD and CuZn-SOD exhibited progressively decreasing activities, those of Mn-SOD and GST were elevated. Neither DNA strand breaks (apoptosis or necrosis) nor changes in PARP-1 activity and in CTGF levels (fibrosis) were observed in the diabetic heart. The absence of cardiomyopathy is accompanied with increased activities of CAT, MnSOD and GST.