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Effect of treatment with olive leaf polyphenols on catalase, superoxide dismutase, and glutathione peroxidase activities in skeletal muscles of diabetic rats

Introduction. Increased reactive oxygen species (ROS) could play an important role in the pathogenesis of many metabolic disorders including diabetes mellitus (DM). Elevated ROS level in DM may be due to decrease the activity of catalase (CAT), superoxide dismutase (SOD) and glutathione peroxidase (GPx). The variation in the levels of these enzymes makes the tissues susceptible to oxidative stress leading to the development of further diabetic complications. Increased ROS production in DM (in both types) can promote muscle weakness and fatigue by altering muscle gene expression and by modification of constitutively expressed proteins, thus, cause contractile dysfunction and protein loss that diminishes muscle mass. The goal of this study was to investigate the effect of olive leaf polyphenols (OLPs) treatment on CAT, SOD and GPx levels in skeletal rat muscle (soleus) of diabetic rats. Materials & methods. DM type 1 was induced by a single administration of streptozotocin (SZT) in male Wistar rats. The blood glucose was monitored at set time intervals. OLPs extracts (512, 768 and 1024 mg/kg) were i.p. administrated during 7-days after induced DM. The activities of CAT, SOD, and GPx were determined in rat soleus muscle. Differences between the groups assessed by an ANOVA one-way, and p<0.05 were considered to be statistically significant. Results. CAT, SOD and GPx activity were significantly changed in rat soleus. SOD and GPx activities markedly decreased in diabetic rats. SOD and CAT activities were significantly increased at the dose of 1024 mg/kg OLP, and GPx activity was increased at the dose of 512 mg/kg. Also, CAT and SOD activities were correlated significantly (R=0.515). Conclusions. Olive leaf polyphenols were efficient for restoring muscle function in diabetic rats. A higher dose of 7-days OLP treatment stimulated the activity of CAT and SOD while lower dose increases the activity of GPx. This study confirms the relationship between a redox-modulating mechanism SOD and CAT and OLPs in diabetic rat muscle.

diabetes mellitus; olive leaf polyphenols; skeletal muscle; oxidative stress

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