Effects of heat stress on respiratory burst, oxidative damage and SERPINH1 (HSP47) mRNA expression in rainbow trout Oncorhynchus mykiss

For rainbow trout Oncorhynchus mykiss, high temperature is a major abiotic stress that limits its growth and productivity. In this study, spleen macrophage respiratory burst (RB), serum superoxide dismutase (SOD), serum malondialdehyde (MDA) and mRNA expression of the SERPINH1 (HSP47) gene in different tissues (liver, spleen, head kidney and heart) were measured in unstressed (18 A degrees C) and heat-stressed (25 A degrees C) fish. Spleen macrophage RB activity, serum SOD activity and MDA content all increased significantly (P < 0.05) during heat shock, and peaked at 8, 12 and 4 h, respectively. SERPINH1 mRNA expression responded in a time- and tissue-specific manner to heat stress, which was mainly reflected in the significant up-regulation in all tissues (P < 0.05) and greater expression in the liver than the other tissues (P < 0.05). During the heat-shock recovery period, the MDA content returned to the unstressed level. These results indicate that heat shock causes cell injury, induces oxidative damage and promotes SERPINH1 mRNA expression, which plays an important protective function during heat stress in O. mykiss. In practice, close attention should be given to temperature changes in O. mykiss production to reduce the effects of high temperature.