Aerobic Training Modulates the Expression of Components of the mPTP Through the Reduction of Oxidative Stress in the Soleus Muscle of Streptozotocin-Induced Diabetic Rats

Background/Objectives: In all types of diabetes, elevated blood glucose levels cause pathological changes in skeletal muscle, primarily due to oxidative stress, mitochondrial dysfunction, and excessive production of reactive oxygen species (ROS). Regular exercise can help mitigate these effects; however, the underlying mechanisms, particularly those involving the mitochondrial permeability transition pore (mPTP), remain incompletely understood. This study aimed to explore the effects of aerobic exercise training (AET) on oxidative stress and the expression of mPTP components in the skeletal muscle of streptozotocin-induced diabetic rats. Methods: Male Wistar rats were randomly divided into three groups: Healthy Sedentary (H-SED), Diabetic Sedentary (D-SED), and Diabetic Exercise-trained (D-EXER); n = 6 per group. The D-EXER group performed AET (0° slope) 5 days/week for 8 weeks. After the intervention period, body weight and fasting blood glucose (FBG) levels were measured, and soleus muscles were collected and analyzed for oxidative stress biomarkers, Western blotting, and gene expression using qRT-PCR. Results: Following an 8-week intervention, AET reduced FBG concentrations. Accordingly, in the soleus muscles of the D-EXER group, ROS levels decreased, and redox balance was improved compared to the D-SED group. Exercise training reduced CypD and Casp9 mRNA expression and increased Bcl-2 mRNA expression, whereas Ant1 mRNA expression was only slightly altered. CypD protein expression was decreased in exercised diabetic rats, while VDAC1 protein and mRNA levels remained unchanged. In the D-EXER group, there were significant inverse correlations between CypD and Casp9 mRNA expression levels and glutathione redox state. Conclusions: The current study suggests that 8 weeks of AET, in addition to reducing hyperglycemia, may favorably influence oxidative balance and the expression of mPTP-related molecular components in diabetic skeletal muscle.