High-intensity interval training attenuates impairment in regulatory protein machinery of mitochondrial quality control in skeletal muscle of diet-induced obese mice.

Mitochondrial quality control processes are essential in governing mitochondrial integrity and function. The purpose of the study was to examine the effects of 10 weeks of high-intensity interval training (HIIT) on the regulatory protein machinery of skeletal muscle mitochondrial quality control and whole-body glucose homeostasis in diet-induced obese mice. Male C57BL/6 mice were assigned to low-fat diet (LFD) or high-fat diet (HFD) group. After 10 weeks, HFD-fed mice were divided into sedentary and HIIT (HFD + HIIT) groups for another 10 weeks ( = 9/group). Graded exercise test, glucose and insulin tolerance tests, mitochondrial respiration, and protein markers of mitochondrial quality control processes were determined. HFD-fed mice exhibited lower ADP-stimulated mitochondrial respiration ( < 0.05). However, 10 weeks of HIIT prevented this impairment ( < 0.05). Importantly, the ratio of Drp1(Ser) over Drp1(Ser) phosphorylation, an indicator of mitochondrial fission, was significantly higher in HFD-fed mice ( < 0.05), but such increase was attenuated in HFD-HIIT compared to HFD (-35.7%,  < 0.05). Regarding autophagy, skeletal muscle p62 content was lower in the HFD group than the LFD group (-35.1%,  < 0.05); however, such reduction was disappeared in the HFD + HIIT group. In addition, LC3B II/I ratio was higher in the HFD group than the LFD group (15.5%,  < 0.05) but was ameliorated in the HFD + HIIT group (-29.9%,  < 0.05). Overall, our study demonstrated that 10 weeks of HIIT was effective in improving skeletal muscle mitochondrial respiration and the regulatory protein machinery of mitochondrial quality control in diet-induced obese mice through the alterations of mitochondrial fission protein Drp1 phosphorylations and p62/LC3B-mediated regulatory machinery of autophagy.