Alterations of erythrocyte free radical defense system, heart tissue lipid peroxidation, and lipid concentration in streptozotocin-induced diabetic rats under coenzyme Q10 supplementation

OBJECTIVE: Free radicals play an important role in genesis and development of various chronic diseases and aging. Our objective is to study the effects of coenzyme Q10 (CoQ10) supplementation on erythrocyte antioxidants, heart tissue lipid peroxidation end products and lipid concentration in different age of diabetic rats.

METHODS: In this study, the activities of superoxide dismutase (SOD), glutathione peroxidase (GSH-Px), and the content of reduced glutathione (GSH) were determined in erythrocytes. The products of lipid peroxidation were determined in the heart tissues of streptozotocin-induced diabetic rats and in healthy rats at 4, 8, and 13-months of age. The above mentioned antioxidant systems of erythrocytes were also determined after supplementation of diabetic and healthy rats with CoQ10. This study was carried out in King Fahad Medical Research Center, Jeddah, Kingdom of Saudi Arabia between 2000 and 2001.

RESULTS: In erythrocytes of diabetic rats the activity of GSH-Px was significantly decreased (p<0.001) in all different age groups, whereas the activity of SOD was significantly increased (p<0.001). However, in erythrocyte of streptozotocin-induced diabetic rats, the concentration of GSH and high-density lipoprotein (HDL)-cholesterol were significantly lower than non-diabetic rats. Moreover, the concentration of heart tissue lipid peroxidation end products, and plasma glucose, cholesterol and triacylglycerol were significantly increased (p<0.001) in all age groups of diabetic rats. Daily supplementation with CoQ10 (10 mg/kg body weight, one month) after induction of diabetes to the rats resulted in the following changes: an increase in both erythrocyte GSH concentration and GSH-Px activity, and slightly increases in plasma HDL-cholesterol. However, SOD activity was significantly decreased (p<0.05). In addition, the levels of lipid peroxidation end products, and triacylglycerol were significantly decreased (p<0.05) in diabetic rats supplemented with CoQ10.

CONCLUSION: The results of the present study indicated that CoQ10 supplementation helps to prevent clinical complications during the course of the disease in diabetic rats.