Alterações hepáticas na expressão gênica e atividade da catalase e superóxido dimutase em ratos diabéticos induzidos por estreptozootocina

The correlation between the type 1 diabetes mellitus and oxidative stress have been described in several studies, however its underlying mechanisms are not fully elucidated. The present work aimed to evaluate the effects of four weeks of streptozootocin-induced (STZ) diabetes in the redox homeostasis of rat hepatocytes. Thus, the liver of male Wistar rats from control and diabetic groups were collected and the activity and expression of antioxidant enzymes, as well the main markers of oxidative stress and content of H2O2 in these tissues were measured. The diabetes induced the activity of superoxide dismutase (SOD) and the gene expression of its mitochondrial isoform, SOD2. However, the expression of SOD1, the cytoplasmic isoform, was reduced by this disease. The activity and expression of catalase (CAT), as well the expression of glutathione peroxidase 1 (GPX1) and peroxiredoxin 4 (PRX4) were drastically reduced in the hepatocytes of diabetics rats. Even with this debility in the peroxidases mRNA expression, the content of H2O2 was reduced in the liver of diabetics rats when compared to the control group. The diabetes caused an increase of lipid peroxidation and a decrease of protein thiol content, showing that this disease causes distinct oxidative effects in different cell biomolecules. Our results indicate that four week of diabetes induced by STZ is already enough to compromise the enzymatic antioxidant systems of the hepatocytes.