Abstract / Summary
Purpose: This study aimed to investigate the protective effects and potential mechanisms of exercise against long-term high-fat diet (HFD)-induced skeletal muscle dysfunction, with a focus on ADP-ribosylation factor 1 (ARF1)-related autophagy–lysosome markers and nuclear factor erythroid 2-related factor 2 (Nrf2) signaling. Methods: Forty male C57BL/6 mice were randomly divided into a normal diet group (DC) and an HFD group, and the latter was further subdivided into a model group (MG), exercise group (EG), Nrf2 inhibitor group (NG), and exercise combined with Nrf2 inhibitor group (ENG) after 12 weeks of HFD feeding. EG received 6 weeks of moderate-intensity treadmill exercise, NG was treated with Nrf2 inhibitor for 6 weeks, and ENG received both the 6-week treadmill exercise and inhibitor injections simultaneously. Serum lipid, blood glucose and insulin resistance indices were detected; skeletal muscle morphology was observed by H&E staining; mRNA and protein expression of ARF1, ULK1, ATP6V0A1 and other factors were determined by RT-qPCR, Western blotting and immunohistochemistry; the oxidative stress index was measured by an ELISA; and the colocalization of ARF1/ATP6V0A1 with the lysosomal marker Lamp1 was analyzed by immunofluorescence. Results: Long-term HFD significantly increased mouse body weight, serum TC, TG, LDL-C, FBG levels and the HOMA-IR index, induced morphological alterations in skeletal muscle (loose myofiber arrangement, abundant intracellular vacuoles), inhibited the mRNA expression of ARF1, ULK1 and ATP6V0A1, and elevated malondialdehyde (MDA) content (p < 0.05 or p < 0.01). Six weeks of moderate-intensity treadmill exercise effectively improved HFD-induced metabolic disorders and skeletal muscle morphological damage, upregulated the expression of ARF1, ULK1 and ATP6V0A1, and reduced oxidative stress (p < 0.05 or p < 0.01). Notably, luteolin-mediated inhibition of Nrf2 signaling may partially reverse exercise-induced alterations in ARF1-related autophagy–lysosome markers and skeletal muscle morphology. Conclusions: Long-term HFD may induce morphological alterations in skeletal muscle, accompanied by changes in ARF1-associated autophagy–lysosome markers and elevated oxidative stress. Conversely, moderate-intensity exercise may ameliorate HFD-related changes in skeletal muscle morphology, potentially via Nrf2 signaling, providing a potential molecular target and theoretical basis for the exercise intervention strategies against HFD-induced metabolic-related skeletal muscle dysfunction.