Effects of Niacin Supplement on SIRT1,p65 and 20S Proteolytic Enzyme in Skeletal Muscle of Rats after a Bout of Non-exhaustive Eccentric Exercise

Objective:To investigate the effects of niacin supplement on rats' exercise-induced muscle damage (EIMD) .Methods:Ninety male Sprague-Dawley (SD) rats were randomly divided into niacin groups (Es) and control groups (Cs) , each of which was further divided into quiet group, immediately after exercise group, 24 h after exercise group, 48 h after exercise group and 72 h after exercise group.SD rats performed eccentric exercise (-16°, 18 m/min, 120 min) .Es received gavage of niacin (10 mg/kg) once a day until the animals were killed.Abdominal aorta blood were harvested for testing creatine kinase (CK) and lactate dehydrogenase (LDH) by enzyme reaction rate and colorimetric method, and soleus muscle for observing morphological change by erosin (HE) staining as well as assessing protein expression of sirtuin 1 (SIRT1) , p65 and 20S protease by western blotting.Results:Niacin supplement reduced percentage of severe inflammatory lesions in muscle skeletal of the EIMD rats at each time point, niacin supplement upregulated SIRT1, inhibited expression of p65 effectively in immediately after exercise group, but there was no significant effect to level of 20S protease and CK and LDH at the any time points respectively.Conclusion:Niacin supplement may reduce inflammatory of rats performed a bout of non-exhaustive eccentric exercise by upregulating SIRT1 and reducing p65 expression, but may not affect expression of 20S protease and levels of serum CK and LDH.