Prevention of Muscle Atrophy by Low-Molecular-Weight Fraction from Hirsutella sinensis Mycelium

Muscle atrophy, an age-related condition, presents a growing healthcare concern within the context of global population aging. While studies have investigated Hirsutella sinensis for its potential antifatigue properties, reports on its active components remain limited. This study evaluated the efficacy of H. sinensis mycelium extract on muscle health, utilizing a 1:1 water-ethanol preparation administered to C57BL/6 mice exhibiting acute hind leg atrophy. The results indicated no adverse effects, with significant improvements in muscle endurance and soleus muscle mass observed over a 14-day period. To further elucidate the mechanisms and effects of H. sinensis mycelium on dexamethasone-induced muscle atrophy, the water extract was fractionated into components of <3.5 kDa, 3.5-10 kDa, and >10 kDa using dialysis membranes. The investigation utilized a C2C12 cell atrophy model, induced by dexamethasone, to analyze the expression of relevant genes via qPCR. The results demonstrated that the <3.5 kDa and >10 kDa fractions significantly upregulated the expression of Myh2 and Myh7 genes while simultaneously downregulating the expression of MuRF-1 and Atrogin-1. It is noteworthy that the <3.5 kDa fraction exclusively enhanced MYHC protein expression and suppressed AMPK expression, as confirmed by Western blot analysis. This comprehensive pilot study suggests that the low-molecular-weight fraction of H. sinensis mycelium exhibits considerable potential for muscle mass preservation and atrophy mitigation. As a result, it offers a promising direction for the development of supplements aimed at addressing fatigue and preventing muscle atrophy.