The effects of different exercise training protocols on mitochondrial dynamics in skeletal and cardiac muscles of Wistar rats

Abstract

Background: Mitochondrial fission and fusion both contribute to maintaining mitochondrial function and optimizing bioenergetic capacity.

Objective: The aim of this study was to compare the effect of aerobic and resistance training on mitochondrial fission and fusion markers in skeletal and cardiac muscles of Wistar rats.

Method: 24 male Wistar rats were randomly divided into four groups of moderate-intensity interval training (MIIT), high-intensity interval training (HIIT), resistance training (RT) and control (CON). The MIIT and HIIT groups performed treadmill exercises with an intensity of 60-65% and 80-85% of the maximum speed, respectively, while the RT group performed resistance training with an intensity of 30-60% of the rat's body weight for 8 weeks. The soleus (SOL), extensor digitorum longus (EDL) and left ventricular tissues were used to evaluate markers of mitochondrial fission and fusion PGC-1α (fusion/fission), Opa-1 (fusion), Fis-1 (fission), Drp-1 (fission), Mfn-1 and Mfn-2 (fusion) genes expression.

Results: In all three tissues, a significant increase in some mitochondrial fusion markers was observed after 8 weeks of training (p = < 0.0001-0.0452). Furthermore, a significant decrease in cardiac mitochondrial fission markers was observed in all three groups (p = < 0.0001-0.0156). This reduction in some markers was evident in the SOL tissue of the HIIT group (p < 0.0001 for Drp-1 and p = 0.0007 for Fis-1) and in the EDL tissue of the RT group (p = 0.0005 for Fis-1 and p = 0.0012 for Drp-1). The mitochondrial fission/fusion markers in the heart (p = 0.0007-0.0449) and SOL (p = 0.0050-0.0258) tissues of the HIIT group had more changes than the RT group, while the mitochondrial fission markers in the EDL tissue of the RT group had a lower level than the HIIT (p = 0.0087 for Drp-1) and MIIT (p = 0.0130 for Fis-1 and p = 0.0010 for Drp-1) groups.

Conclusion: Our study demonstrated that HIIT, through better regulation of mitochondrial fusion and fission than RT, improves mitochondrial dynamics in cardiac and SOL tissues.

Keywords: Exercise; Mitochondrial dynamics; Muscles; Myocardium; Rats.

Fig. 1

Final weight of rats in study groups (The data presented as mean ± SEM). ‡: significant differences between HIIT and RT groups, §: significant differences between MIIT and RT groups. CON: control, MIIT: moderate-intensity interval training, HIIT: high-intensity interval training, RT: resistance training

Fig. 2

The effect of training on the gene expression of mitochondrial indices in SOL muscle (The data presented as mean ± SEM). (a) Mfn-1 gene expression, (b) Mfn-2 gene expression, (c) Opa-1 gene expression, (d) PGC-1α gene expression, (e) Drp-1 gene expression, (f) Fis-1 gene expression. *significant differences between HIIT and CON groups, #: significant differences between MIIT and CON groups, †: significant differences between RT and CON groups, ‡: significant differences between HIIT and RT groups, £: significant differences between HIIT and MIIT groups. CON: control, MIIT: moderate-intensity interval training, HIIT: high-intensity interval training, RT: resistance training, SOL: soleus, Mfn-1: mitofusin-1, Mfn-2: mitofusin-2, Opa-1: optic atrophy-1, PGC-1α: peroxisome proliferator-activated receptor gamma co-activator 1 alpha, Drp-1: dynamin-related protein-1, Fis-1: mitochondrial fission-1

Fig. 3

The effect of training on the gene expression of mitochondrial indices in EDL muscle (The data presented as mean ± SEM). (a) Mfn-1 gene expression, (b) Mfn-2 gene expression, (c) Opa-1 gene expression, (d) PGC-1α gene expression, (e) Drp-1 gene expression, (f) Fis-1 gene expression. *significant differences between HIIT and CON groups, #: significant differences between MIIT and CON groups, †: significant differences between RT and CON groups, ‡: significant differences between HIIT and RT groups, §: significant differences between MIIT and RT groups. CON: control, MIIT: moderate-intensity interval training, HIIT: high-intensity interval training, RT: resistance training, EDL: extensor digitorum longus, Mfn-1: mitofusin-1, Mfn-2: mitofusin-2, Opa-1: optic atrophy-1, PGC-1α: peroxisome proliferator-activated receptor gamma co-activator 1 alpha, Drp-1: dynamin-related protein-1, Fis-1: mitochondrial fission-1

Fig. 4

The effect of training on the gene expression of mitochondrial indices in heart muscle (The data presented as mean ± SEM). (a) Mfn-1 gene expression, (b) Mfn-2 gene expression, (c) Opa-1 gene expression, (d) PGC-1α gene expression, (e) Drp-1 gene expression, (f) Fis-1 gene expression. *significant differences between HIIT and CON groups, #: significant differences between MIIT and CON groups, †: significant differences between RT and CON groups, ‡: significant differences between HIIT and RT groups. CON: control, MIIT: moderate-intensity interval training, HIIT: high-intensity interval training, RT: resistance training, Mfn-1: mitofusin-1, Mfn-2: mitofusin-2, Opa-1: optic atrophy-1, PGC-1α: peroxisome proliferator-activated receptor gamma co-activator 1 alpha, Drp-1: dynamin-related protein-1, Fis-1: mitochondrial fission-1