Peptides obtained by enzymatic decomposition of mackerel induce recovery from physical fatigue by enhancing the SIRT1-mediated antioxidant effect in the soleus muscle of mice.

Fatigue is a serious health problem, and long-term fatigue can lead to mental illnesses and accelerated aging. Oxidative stress, which causes excessive production of reactive oxygen species, is generally thought to increase during exercise and is an indicator of fatigue. Peptides obtained by enzymatic decomposition of mackerel (EMP) contain selenoneine, a strong antioxidant. Although antioxidants increase endurance, the effects of EMP on physical fatigue are unknown. The present study aimed to clarify this aspect. We investigated the effects of EMP on changes in locomotor activity, expression levels of silent mating type information regulation 2 homolog peroxisome 1 (SIRT1), proliferator-activated receptor-γ coactivator-1α (PGC1α), and antioxidative-related proteins including superoxide dismutase 1 (SOD1), SOD2, glutathione peroxidase 1, and catalase in the soleus muscle following EMP treatment before and/or after forced walking. Treatment with EMP before and after forced walking, and not only at one or another time point, improved the subsequent decrease in the locomotor activity and enhanced the levels of SIRT1, PGC1α, SOD1, and catalase expression in the soleus muscle of mice. Moreover, EX-527, a SIRT1 inhibitor, abolished these effects of EMP. Thus, we suggest that EMP combats fatigue by modulating the SIRT1/PGC1α/SOD1-catalase pathway.