The effect of regular exercise training on gene expression of Autophagy related protein 5 (ATG5) and Autophagy relatedprotein 7 (ATG7) of white adipose tissue of mice with a high-fat diet

Previous studies have shown that Autophagy (lysosome-dependent self-degradation) is upregulated in white adipose tissue of obese subjects. Autophagy-related proteins i.e ATG5 and ATG7 play an essential role in the early stage of the autophagic process. On the other hand, it was found that exercise training modified the bad regulation and maladaptation of white adipose tissue by many molecular mechanisms. Therefore, a question remains to be elucidated whether exercise training can modulate the upregulation of Autophagy induced by a high-fat diet and Autophagy seen in obese subjects. Thus, the present study aimed to survey the effect of regular exercise training on gene expressions of ATG5 and ATG7 in white adipose tissue of mice fed a high-fat diet.

Twenty-one C57BL/6 male mice (age of four weeks; Approximate body weight of 12 grams) were purchased from the experimental and comparative studies center of Iran University of Medical Sciences. The mice were randomly assigned to three groups: Control (C, n=7), 2) High-fat diet (HFD, n=7), and  High-fat diet with exercise training (HFD-ET, n=7). The mice of the HFD group were fed a high-fat diet (42% kcal of fat) for 12 weeks. The mice of the HFD-ET group were submitted to continuous running on a treadmill for six weeks along with feeding HFD. After the experiment, mice were sacrificed, and visceral adipose tissue pads (epididymal fat) were surgically collected. The Real-Time–PCR methods were used to measure the mRNA expression of ATG5 and ATG7. Data of research were statically analyzed by One-way Analysis of Variance (ANOVA) followed by Tukey's post hoc test.

Results:

 Data showed that the mRNA expression of ATG5 and ATG7 were higher over two-fold in the HFD group as compared to the control group (p<0.05). Further, the mRNA expression of these genes was higher in the HFD-ET group compared to the control group (p<0.01). Interestingly, the mRNA expression of ATG7 was 1.5 fold higher in the HFD-ET group compared to the HFD group (p<0.05). However, the mRNA expression of ATG5 was not significantly changed in the HFD-ET group as compared to the HFD group (p>0.05).

Conclusion:

These results indicate that long-term feeding high-fat diet causes upregulating of the gene expression of key factors involved in the early stage of the autophagy process (i.e ATG5 and ATG7). Regular exercise training could augment the HFD-induced upregulation of ATG7 gene expression. However, it could not change the HFD-induced upregulation of ATG5 gene expression. Based on the results could be speculated that exercise training accompanied by a high-fat diet may more stimulate the autophagy mechanism in white adipose tissue, probably resulting in a positive adaptation in white adipose tissue development.