LAUSR

ABSTRACT Purpose Exhaustive exercise induces acute liver stress; however, the precise mechanisms remain unclear. Methods We investigated the effects of neutrophil depletion in male C57BL/6J mice. Male C57BL/6J mice were divided into four groups: sedentary with control antibody (n = 20), sedentary with antineutrophil antibody (n = 20), exhaustive exercise with control antibody (n = 20), and exhaustive exercise with antineutrophil antibody (n = 20). Antineutrophil antibodies (1A8) or control antibodies were administered intraperitoneally before running on a treadmill. Immediately and at 24 h after running to exhaustion on a treadmill at a 7% gradient and a speed of 24 m·min−1, blood neutrophil counts were measured by flow cytometry. Plasma activities of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were also measured. Hematoxylin–eosin staining was performed to calculate the liver stress score, and hepatic tumor necrosis factor-α was measured using enzyme-linked immunosorbent assay. Results Exercise increased blood neutrophil and neutrophil infiltration into the liver. Plasma AST and ALT activities were significantly higher immediately after exhaustive exercise than after sedentary control (AST, sedentary with control antibody: 52.2 ± 0.4, exhaustive exercise with control antibody: 210.0 ± 19.8; ALT, sedentary with control antibody: 29.8 ± 2.2, exhaustive exercise with control antibody: 87.2 ± 15.8). However, AST and ALT activities were significantly decreased with the 1A8 antibody (AST, 102.2 ± 12.9; ALT, 39.2 ± 4.0). In addition, the liver stress score increased after exercise but was significantly reduced by prior 1A8 antibody administration. The 1A8 antibody treatment also decreased hepatic tumor necrosis factor-α levels after exhaustive exercise. Conclusions These results suggested that neutrophils play a critical role in increasing liver stress by regulating inflammation.