Effects of eight weeks of high-intensity interval training on the expression of Pink1 and Parkin proteins in the liver tissue of type 2 diabetic male rats

There is a close relationship between liver mitochondrial dysfunction and the development of obesity and insulin resistance. As observed in type 2 diabetes, in conditions of insulin resistance, a decrease in insulin sensitivity of liver cells, skeletal muscle and fat cells is observed. In recent decades, physical activity has become a key tool in controlling many diseases, including type 2 diabetes, and studies have shown that various training protocols are effective in reducing the epidemic and improvement of some metabolic functions of the liver. The purpose of this study was to evaluate the effect of eight weeks of high intensity interval training (HIIT) on Parkin and Pink1 proteins in the liver tissue of type 2 diabetic rats.

In an experimental design, 30 three-month-old adult male Wistar rats with a weight range of 250-300 g were randomly divided into three groups of 10 including healthy control (C: intraperitoneal injection of saline), Diabetic control (D: diabetic with high-fat diet combined with intraperitoneal injection of streptozotocin) and trained diabetic (D+T: diabetic with exercise) were divided. The training protocol encompassed running at an intensity of 85%-90% of the maximum speed in 6 to 12 two-minute intervals; 5 days a week for eight weeks. Fourty eight hours after the last training session and after 12 to 14 hours of fasting, all rats were anesthetized and operated by a trained specialist without pain. A method based on Western blotting was used to determine changes in the expression profile of Parkin and Pink1 proteins in the heart muscle tissue (left ventricle) of rats. The two-way analysis of variance and Bonferroni’s post-hoc test were used to analyze the data.

Induction of diabetes (D) causes a 51% and 63% increase in Parkin and Pink1 proteins, respectively, although it is not statistically significant (P>0.05). In addition, exercise intervention caused a 45% and 38% decrease in Parkin and Pink1 in the trained diabetic group (D+T) compared to the diabetic group (D), but it was not significant (p≥0.05).

According to the results, it can be stated that eight weeks of HIIT is insufficient to observe a significant reduction of mitophagy in the liver tissue of diabetic rats. At the same time, based on the partial changes of the indices, HIIT might be a preventive measure against the abnormal increase of mitophagy as a result of type 2 diabetes. However, to making a definite conclusion about these indices and how they are affected by different conditions more researches are needed.