Effect of spermidine intake on skeletal muscle regeneration after chemical injury in male mice.

Skeletal muscle has a high regenerative ability and maintains homeostasis by rapidly regenerating from frequent damage caused by intense exercise or trauma. In sports, skeletal muscle damage occurs frequently due to intense exercise, so practical methods to promote skeletal muscle regeneration are required. Recent studies have shown that it may be possible to promote skeletal muscle regeneration through new pathways, such as promoting autophagy and improving mitochondrial function. Spermidine is a type of polyamine, and oral intake of spermidine promotes autophagy and improves mitochondrial function without inhibiting mTOR. Therefore, we evaluate the effects of spermidine intake on skeletal muscle regeneration after injury using a mouse model of cardiotoxin-induced muscle injury. Our results showed no significant change in skeletal muscle wet weight with spermidine intake at all time points. In addition, although spermidine intake significantly increased the mean fiber cross-sectional area 14 days after injury, these effects were not observed at other time points. In addition, we analyzed stem cells, autophagy, mTOR signaling, inflammation, and mitochondria, but no significant effects of spermidine intake were observed at almost all time points and protein expression levels. Therefore, spermidine intake does not affect skeletal muscle regeneration after chemical injury, and if there is any, it is very limited.