سارا فرج پور خزاعی

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.

Dysfunction of mitochondria is associated with such diseases as obesity, cancer, and type 2 diabetes. Training plays a major role in the improvement of mitochondrial damage and oxidative stress. Therefore, the present study aimed to investigate the effect of eight weeks of high-intensity interval training on some mitophagy indices in the liver tissue, including BNIP3 and NIX in type 2 diabetic rats.

A total of 30 three-month-old adult male Wistar rats with a weight range (250-300 g) were randomly assigned to four groups of 10 series, including healthy control (C), Diabetic control (D), and diabetic+Training (D+T). The training protocol includes running with intensity at 85%-90% of maximum speed in 6-12 two-minute intervals five days a week for eight weeks. A method based on Western blotting was used to determine changes in the expression of BNIP3 and NIX proteins in the liver tissue of rats. The one-way analysis of variance and the Bonferroni post hoc test were used to analyze the data.

Diabetes increased BNIP3 and NIX proteins; nonetheless, it was not significant. The changes of NIX in the trained diabetic group were about 57% less than in the diabetic control group, and this difference was significant (P=0.033), while BNIP3, despite a 37% decrease, did not change significantly (P>0.05).

Eight weeks of intense intermittent training caused a significant decrease in the expression of proteins involved in mitophagy in the training group. Nonetheless, arriving at a definite conclusion on these indicators and how they are affected by different conditions depends on conducting further studies.

Leptin resistance is an important risk factor for obesity. So, the present study was conducted in order to determine the effectiveness of one-month concurrent training with and without caffeine ingestion on the resting energy expenditure and leptin resistance in overweight women. 20 non-athlete and overweight women in a double-blind and quasi-experimental designs in the two groups pre-post intervention (concurrent training group + placebo and concurrent training group + caffeine) for 4 weeks of a concurrent training (three sessions per week for 1.5 hours per session; aerobic training with an intensity between 65-85% heart rate reserve and resistance training with an intensity of 70-75% of one repetition maximum) with and without caffeine (5 mg.kg-1.day). Changes in resting energy expenditure and leptin resistance during two phases (baseline and 24 hours after completing the training period). Serum fasting leptin levels significantly reduced in both groups following one month period of concurrent training (p=0.04). However, there was no significant difference between the two groups. Also, caffeine supplementation administered together with concurrent training could increase resting expenditure energy (REE) and decrease leptin resistance index after one month (p=0.032). Based on the findings of this study, it can be concluded that one month of aerobic-resistance concurrent training in both groups, especially with considering the further reduction of the indices studied in the caffeine consumer group; maybe prevent the risk factors associated with obesity in overweight women.