Heat stress triggers an antioxidant response in porcine skeletal muscle

Abstract

Heat stress (HS) is a major concern for the swine industry as it negatively impacts pig production efficiency. Also, heat related illnesses remain a serious concern for human health. HS pigs exhibit reduced feed intake and diminished growth rate, still, little is known about the molecular effects of HS on pig skeletal muscle. This study aimed to determine the extent to which HS disrupts redox balance in pig red semitendinosus (STR) muscle. Crossbred gilts were subjected to thermoneutral (TN; 20°C) or heat stress (35°C) conditions for 1, 3 or 7 days. To account for reduced feed intake in HS animals a group of TN animals were pair fed to mimic intake of 7 day HS animals. To assess redox imbalance in STR, nitrotyrosine and MDA, markers of oxidatively modified proteins, were measured by Western blots. Additionally, catalase activity, a major antioxidant enzyme, was measured. Nitrotyrosine was similar between all treatment groups; however, 1 and 3 days of HS decreased MDA content by 25% (P<0.05) in HS pigs compared to TN pigs, but recovered to TN levels after 7 days of HS. Catalase activity increased ~30% after 1 day of HS (P<0.05), though after 3 days of HS catalase activity was similar to TN. These results suggest that there is an initial antioxidant response to HS to alleviate free radical injury, however this response is not sustained. Supported by USDA/NIFA Grant No. 2011–67003‐30007.