The effects of high and moderate intensity interval training on skeletal muscle of TFAM and NRF1 in type 2 diabetic male rats

It is well recognized that mitochondrial transcription factor A (TFAM) and nuclear respiratory factor-1 (NRF-1) are the key regulators of mitochondrial biogenesis and oxidative phosphorylation. This study investigated whether 12 weeks of interval training with high (HIIT) and moderate (MIIT) intensity influences the key regulatory molecules of mitochondrial biogenesis (TFAM and NRF-1( of skeletal muscle in type 2 diabetic male rats.

Forty male rats (age: 8 weeks, weight: 180±20 g) were divided into two groups: high fat diet (HFD) including 32 rats, and standard diet (C) including 8 rats. After inducing type 2 diabetes via Streptozotocin, 8 diabetic rats (D) and 8 rats in group C were sacrificed and the remaining 24 rats were randomly assigned to three groups including diabetic control (DC), MIIT, and HIIT. The MIIT protocol includes 13 bouts of 4-minute activity with an equivalent intensity of 60-65% VO2max and the HIIT protocol includes 10 bouts of 4-minute activity with the equivalent intensity of 85-90% VO2max with 2 minute active rest periods that was performed for 12 weeks, and 5 sessions per week. Western blotting was used to measure the levels of TFAM and NRF1 proteins; and the parametric and non-parametric tests were used to analyze the data at the p≤0.05 level.

The results showed that TFAM and RNF-1 protein levels were significantly decreased in the D group compared to the C group (p<0.01). Indeed, exercise training resulted in an insignificant increase in protein levels of NRF-1 compared to the DC group (p>0.05); while HIIT and MIIT had no significant effect on protein levels of TFAM (p>0.05).

It seems that the HIIT and MIIT programs improve mitochondrial respiration but have no effect on mitochondrial biogenesis in type 2 diabetic rats. However, further research is needed for definite results.