engleski

Olive leaf polyphenols attenuate oxidative stress in rat skeletal muscle after streptozotocin- induced type 1 diabetes

Introduction. Hyperglycemia resulting from uncontrolled glucose regulation is widely recognized as the causal link between diabetes and diabetic complications, as well as increased oxidative stress that could affect the function of skeletal muscle. Skeletal muscle possesses a well- developed system to regulate reactive oxygen species (ROS) and prevent potentially deleterious effects including both mitochondrial and cytosolic isoforms of superoxide dismutase (SOD), catalase (CAT) and glutathione peroxidase (GPx) enzymes, and a number of direct scavengers of ROS. The goal of this study was to investigate the effect of olive leaf polyphenols on hyperglycemia- induced ROS generation in skeletal muscle of diabetic rats. Materials & methods. Diabetes was induced by a single administration of streptozotocin (SZT) in male Wistar rats. The blood glucose was monitored at set time intervals. Well characterized olive leaf polyphenols (OLPs) were i.p. administrated during seven days after SZT-induced diabetes. Total antioxidant capacity (TAC), CAT, SOD, GPX and total protein thiols (TPT) were determined in rat muscle. Results. PFEs treatment markedly increased TAC and SOD activity in skeletal muscle soleus of OLPs treated rats compared with SZT rats. Cytosolic GPx and CAT activity in muscle were increased, as well as the amount of TPT. However, the highest level of TAC and the highest activity SOD were found in the mitochondrial fraction. Conclusions. Treatment with OLPs for 7 days in diabetic rats stimulated activity of CAT and reduced the level of cellular ROS. This study suggested that polyphenols act through a redox- modulating mechanism rather than through direct free radical scavenging.

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

Potpore Sveučilišta u Rijeci br. 13.11.1.2.02 i 13.06.1.2.42.