Effect of the resistive training on the mitochondrial dynamic of extensor digitorum longus of rats exposed to a second-hand smoke

• Grant number: 24/11081-6
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: February 01, 2025
• End date: December 31, 2025
• Field of knowledge: Biological Sciences - Physiology - Physiology of Organs and Systems
• Principal Investigator: Patricia Monteiro Seraphim
• Grantee: Gabriel Evangelista dos Santos
• Host Institution: Faculdade de Ciências e Tecnologia (FCT). Universidade Estadual Paulista (UNESP). Campus de Presidente Prudente. Presidente Prudente , SP, Brazil

Abstract

Smoking is a serious public health problem, causing over 7 million deaths annually and associated with diseases such as atherosclerosis, fibrosis, COPD, and lung cancer. Additionally, it is linked to oxidative stress, inflammation, and protein imbalance, affecting fundamental cellular processes such as mitochondrial biogenesis. Mitochondria play a crucial role in muscle cells, providing energy for muscle contraction, but excessive production of Reactive Oxygen Species (ROS) during exercise and exposure to cigarette smoke can lead to mitochondrial dysfunction. Besides ATP production, they also work in regulating energy metabolism where maintaining cellular integrity depends on vital processes of mitochondrial fusion and fission, ensuring proper mitochondrial function. Fusion allows the exchange of content between organelles, while fission eliminates irreversible damage. These processes are controlled by large dynamic GTPases with antagonistic functions. Fission is mainly mediated by DRP1, recruited to the mitochondrial surface, and Fis1, which acts as a DRP1 receptor, forming a complex that divides the mitochondrion through GTP hydrolysis. Fusion is regulated by Mfn1, Mfn2, and OPA1, where Mfn1 and Mfn2 facilitate the joining of mitochondria in the outer membrane, and OPA1 promotes inner fusion. Cigarette smoke, rich in toxic substances, increases the risk of lung cancer and affects the translocation of the glucose transporter GLUT4, potentially triggering insulin resistance and other metabolic complications. Quitting smoking and exercising are effective strategies to mitigate health risks and improve quality of life. Previous studies conducted by our laboratory have highlighted the effects of smoking on mitochondrial dynamics during resistance exercise, potentially reducing deleterious effects even under smoke influence, as well as preventing the increase in left ventricular thickness in rats, preserving mitochondrial function, and promoting beneficial effects for maintaining prostatic morphology and normal protein levels. Objectives: 1) To analyze the impact of 16 weeks of exposure to secondary smoking on the protein levels of mitochondrial dynamics of glycolytic muscle fibers in Wistar rats; 2) To evaluate the effect of resistance training on the protein levels of mitochondrial dynamics of glycolytic muscle fibers in secondary smoking rats. Materials and Methods: Long extensor digitorum muscle tissues of the fingers (EDL) from male Wistar rats will be evaluated. They will be divided into the following groups: Control (C), Smoker (S), Exercised (E), and Exercised Smoker (ES). Groups S and ES will be exposed to the smoke of 4 cigarettes for 30 minutes, twice a day, 5 times a week, for 16 weeks. Groups E and ES will perform four climbs with progressive load, once a day, 5 times a week, for 16 weeks. The long extensor muscle of the digits (EDL) will be collected for evaluation of oxygen consumption and mitochondrial protein expression. Tissue protein content will be extracted using lysis buffer, protein concentration will be evaluated by the Bradford method, and the analysis and evaluation of the expression content of the mitochondrial fission proteins FIS1 and DRP1 will be performed by Western Blotting. Mitochondrial fusion proteins OPA1 and MFN2 will also be evaluated by Western Blotting. Two-way ANOVA will be used for statistical analysis, with P<0.05 as the level of significance.