Efeitos do treinamento físico no tecido muscular da prole de animais expostos à poluição do ar

Abstract

Air pollution is a relevant environmental risk factor associated with respiratory and cardiovascular diseases, as well as impaired fetal development. Evidence suggests that intrauterine exposure to pollutants may programme metabolic and inflammatory alterations in offspring; however, its effects on skeletal muscle and possible sex differences remain poorly understood. Physical exercise has emerged as a non-pharmacological strategy capable of attenuating these effects through modulation of inflammation, oxidative stress, and beneficial muscular adaptations. This study aimed to investigate the effects of exercise training on skeletal muscle tissue in male and female offspring exposed to air pollution during gestation. Female Wistar rats were exposed to fine particulate matter (PM₂.₅; 600 μg/m³) from the 5th day post-conception until delivery. After weaning, offspring were allocated into six experimental groups: male control (MC), female control (FC), exposed male (ME), exposed female (FE), exposed trained male (MET), and exposed trained female (FET) (n = 6–8 animals/sex/group). Trained groups underwent a moderate aerobic treadmill training protocol (5x/wk, 8 wks). At the end of the protocol, a maximal exercise test was performed, and the gastrocnemius muscle was collected for analysis of muscle mass, inflammatory mediators and oxidative stress markers. Exercise training increased physical capacity and maximal exercise performance in the MET and FET groups. Maternal exposure to PM₂.₅, despite not altering muscle mass, induced increased IL-6 levels in males and reduced IL-10 levels in both males and females. Trained groups of both sexes showed a reduction in the muscular TNF-α/IL-10 ratio. Muscular SOD activity was reduced and H₂O₂ levels increased in the ME group compared with the MC group, which was not observed in the MET group. FRAP levels were reduced in the FE group compared with the FC group, which was not observed in trained groups. Exercise training reduced NADPH oxidase activity and lipid peroxidation in male skeletal muscle. No differences were observed for GPx, protein carbonyls, or nitrite. In males, the TNF-α/IL-10 ratio showed positive correlations with H₂O₂ (r = 0.69; p = 0.01), NADPH oxidase (r = 0.64; p = 0.04), and TBARS (r = 0.70; p = 0.01), and negative correlations with SOD (r = -0.63; p = 0.02) and exercise test duration (r = -0.73; p = 0.02). In females, a positive correlation was observed between the TNF-α/IL-10 ratio and NADPH oxidase (r = 0.71; p = 0.03), and negative correlations were observed between the TNF-α/IL-10 ratio and SOD (r = -0.70; p = 0.04), FRAP (r = -0.72; p = 0.03), and exercise performance (r = -0.74; p = 0.02). Positive correlations were also observed between maximal exercise performance and gastrocnemius muscle mass in males (r = 0.64; p = 0.05) and females (r = 0.60; p = 0.05). Gestational exposure to PM₂.₅ promoted early inflammatory and redox alterations in offspring skeletal muscle, with greater susceptibility in males and association with impaired functional performance. Postnatal exercise training attenuated these effects and improved functional capacity. Collectively, these findings reinforce the role of regular physical exercise as a relevant non-pharmacological strategy to mitigate the repercussions of intrauterine exposure to air pollution on skeletal muscle, with potential implications for preventing metabolic and functional outcomes throughout life.