Sulforaphane enhances Nrf2-mediated antioxidant responses of skeletal muscle induced by exhaustive exercise in HIIT mice

Nuclear factor erythroid-derived 2-like 2 (Nrf2) is the master regulator of antioxidant defenses. High-intensity interval training (HIIT) has been proposed as a time-efficient training program and has become a substantial component of modern training program. In the present study, we evaluated the effects of sulforaphane (SFN), a dietary isothiocyanate derived from cruciferous vegetables and a potent Nrf2 activator, on Nrf2-mediated antioxidant defense responses of skeletal muscle induced by exhaustive exercise in HIIT mice. Male C57BL/6J mice were randomly allocated into control group, HIIT group, and HIIT pretreated with SFN (HIIT+SFN) group. On the third day after completion of a 6-weeks HIIT protocol, an exhaustive treadmill test was conducted in all mice. Mice were intraperitoneally injected with SFN (HIIT+SFN group) or PBS (HIIT and control mice) 4 times in 3 days prior to the exhaustive treadmill test. The results indicated that the 6-weeks HIIT protocol did not increase the antioxidative capacity of skeletal muscle during exhaustive exercise. Importantly, SFN treatment improved antioxidative capacity of skeletal muscle in response to the acute exhaustive exercise by increasing mRNA and nucleoprotein expression of Nrf2 and these genes involved in antioxidant generation and decreasing blood creatine kinase (CK) and 4-hydroxy-2-nonenal (4-HNE)-modified protein levels in the HIIT mice.