Effect of electrical stimulation-induced resistance exercise on mitochondrial fission and fusion proteins in rat skeletal muscle

Abstract

It is well known that resistance exercise increases muscle protein synthesis and muscle strength. However, little is known about the effect of resistance exercise on mitochondrial dynamics, which is coupled with mitochondrial function. In skeletal muscle, mitochondria exist as dynamic networks that are continuously remodeling through fusion and fission. The purpose of this study was to investigate the effect of acute and chronic resistance exercise, which induces muscle hypertrophy, on the expression of proteins related to mitochondrial dynamics in rat skeletal muscle. Resistance exercise consisted of maximum isometric contraction, which was induced by percutaneous electrical stimulation of the gastrocnemius muscle. Our results revealed no change in levels of proteins that regulate mitochondrial fission (Fis1 and Drp1) or fusion (Opa1, Mfn1, and Mfn2) over the 24-h period following acute resistance exercise. Phosphorylation of Drp1 at Ser616 was increased immediately after exercise (P < 0.01). Four weeks of resistance training (3 times/week) increased Mfn1 (P < 0.01), Mfn2 (P < 0.05), and Opa1 (P < 0.01) protein levels without altering mitochondrial oxidative phosphorylation proteins. These observations suggest that resistance exercise has little effect on mitochondrial biogenesis but alters the expression of proteins involved in mitochondrial fusion and fission, which may contribute to mitochondrial quality control and improved mitochondrial function.

Effects of clenbuterol administration on mitochondrial morphology and its regulatory proteins in rat skeletal muscle

“…These protein levels also associated with alteration in muscle fiber composition. Denervation decreases mitochondrial volume with down‐regulation of mitochondrial fusion proteins Opa1 and Mfn2 (Iqbal et al, ; Kitaoka et al, ), whereas chronic contractile activity leads to reticular mitochondria with up‐regulation of these proteins (Iqbal et al, ; Kitaoka et al, ). These findings suggest that slow‐to‐fast fiber type transition decreased mitochondrial volume and dynamics protein levels.…”

Mitochondria Initiate and Regulate Sarcopenia

“…Studies in rodents have shown an increased abundance of autophagy proteins including Drp1 and Bcl-2 and 19 kDa interacting protein-3 (Bnip3) after exercise (60, 65, 71, 78). Bnip3 functions as a mitophagy receptor to recruit selected autophagosomes for elimination.…”

Adaptations of Skeletal Muscle Mitochondria to Obesity, Exercise, and Polyunsaturated Fatty Acids

“…In line with this, during acute endurance exercise, mRNA levels of MFN1 and MFN2 (markers of mitochondrial fusion) were increased at 12 and 24 h after exercise in humans and rats, partly mediated by the PGC1α/ERRα pathway (Cartoni et al, ; Ding et al, ). In addition, MFN1, MFN2, and OPA1 protein levels were elevated 24 and 48 h after long‐term resistance or endurance exercise training in the rats and mice skeletal muscle (Greene et al, ; Ju et al, ; Kitaoka, Ogasawara, Tamura, Fujita, & Hatta, ). However, the above mitochondrial fusion markers seemed to have no change or decreased expression immediately and 1 h after exercise (Bori et al, ; Cartoni et al, ; Ding et al, ; Jamart, Naslain, Gilson, & Francaux, ; Kitaoka et al, ).…”

“…In addition, MFN1, MFN2, and OPA1 protein levels were elevated 24 and 48 h after long‐term resistance or endurance exercise training in the rats and mice skeletal muscle (Greene et al, ; Ju et al, ; Kitaoka, Ogasawara, Tamura, Fujita, & Hatta, ). However, the above mitochondrial fusion markers seemed to have no change or decreased expression immediately and 1 h after exercise (Bori et al, ; Cartoni et al, ; Ding et al, ; Jamart, Naslain, Gilson, & Francaux, ; Kitaoka et al, ). Therefore, mitochondrial fusion in the skeletal muscle may depend on timepoints of exercise.…”

“…Both endurance and resistance exercise have been linked to an increase in markers of mitochondrial fission, including FIS1, DRP1, and phosphorylation of DRP1 (Ser616), in the skeletal muscle (Ding et al, 2010;Jamart et al, 2013;Ju et al, 2016;Kitaoka et al, 2015), although some studies showed no changes in these markers (Bori et al, 2012;Greene et al, 2015). It has been suggested that mitochondrial fragmentation would help clear damaged mitochondria and allow incorporation of newly synthesized mitochondria, resulting in an improvement of mitochondrial quality (Pagano, Py, Bernardi, Candau, & Sanchez, 2014).…”