Adaptive changes of antioxidant status in development of experimental diabetes.

BACKGROUND

In clinical and experimental research, attention is paid to the role of antioxidant defense systems in the prevention of diabetic complications. Little information is available about regulation of the endogenous level of antioxidants in the state of chronic oxidative stress in relation to the development of diabetes, and particularly about coenzyme Q as one of the most important endogenous antioxidants with an irreplaceable function in mitochondrial bioenergetics.

PURPOSE

To examine changes in concentrations of two important lipophilic antioxidants, coenzyme Q9 and alpha-tocopherol, in rat tissues during the development of experimental diabetes.

METHODS

Experimental diabetes in male Wistar rats, was induced by streptozotocin in the dose of 55 mg/kg intravenously. Coenzyme Q9 (CoQ9) and alpha-tocopherol (alpha-toc.) were determined in myocardial and skeletal muscles and in kidney tissue after 1, 6 and 8 months of diabetes duration by the method of high-performance liquid chromatography.

RESULTS

Myocardial CoQ9 content increased progressively in the course of diabetes development by 14, 29 and 61%, while in skeletal muscles and kidney, the increases were not dependent on the duration of diabetes. The content of alpha-toc. increased in the myocardium after 8 months of diabetes duration, in kidney tissue and skeletal muscles, it did not change in comparison with control rats.

CONCLUSIONS

An increased content of the lipophilic antioxidants coenzyme Q9 and alpha-tocopherol in tissues of diabetic rats is regarded as an adaptation of the antioxidant defense system to chronic oxidative stress. The exact mechanisms of accumulation of these antioxidants in diabetic tissues could be elucidated by studies investigating their relation to changes in lipid content and to the total of bioenergetic and antioxidant capacities. (Fig. 3, Ref. 25.)