The Injection of miR-1/133 Antagonist Notably Accelerated the Healing Process of Exercise-Induced Skeletal Muscle Injury.

Exercise-induced muscle damage (EIMD) significantly impacts daily work and life. The rapid promotion of repair for EIMD is worthy of attention. This study aimed to investigate the effect and mechanism of microRNAs in treating EIMD. By establishing an acute skeletal muscle injury model, we determined the key time point for skeletal muscle injury repair and the time-specific changes in MRTF-A/Pax7/SRF and muscle regeneration factors during the repair process. MicroRNAs antagonists were injected to verify the targeting relationship between miR-1/133a and MRTF-A/Pax7/SRF. A single bout of acute eccentric exercise caused significant damage to the morphological ultrastructure of rat gastrocnemius muscles, with the most severe injuries occurring 72 h after exercise. At this particular time point, it was identified as crucial for damage repair. Both miR-1-3p and miR-133a-3p collectively targeted and suppressed the protein translation of MRTF-A, Pax7, and SRF. Furthermore, both miR-1-3p and miR-133a-3p antagonists targeted the MRTF-A/Pax7 axis as well as the MRTF-A/SRF axis. MiR-1-3p antagonists primarily promote muscle proliferation and differentiation, while miR-133a-3p antagonists mainly promote differentiation while inhibiting atrophy. Combined injection effectively promote both muscle proliferation and differentiation while inhibiting atrophy, thereby facilitating damage repair in skeletal muscle fiber structure. Key words Exercise " Muscle damage " Skeletal muscle regeneration " MRTF-A " Pax7 " SRF.