摘要

Six semipurified diets of graded histidine levels (from 4.1 to 14.2 g/kg) were fed to fish for 8 weeks. The results showed that the intestinal content of malondialdehyde (MDA), activities of total superoxide dismutase (T-SOD) and glutathione peroxidase (GPx) were noticeably lower in 8.0 g/kg diet compared to control group. While the lowest activities of copper-zinc superoxide dismutase (Cu/Zn-SOD) and manganese superoxide dismutase (Mn-SOD) were observed in 9.9 g/kg diet, the intestinal activities of total antioxidant capacity (T-AOC) and catalase (CAT) in 14.2 g/kg diet were noticeably higher than those in 8.0 and 9.9 g/kg diets. Plasma biochemical indexes were not significantly affected by dietary histidine levels. In the intestine, the Kelch-like ECH-associated protein 1 (Keap1) mRNA levels were increased in 8.0 g/kg diet, which suppressed the nuclear translocation of nuclear factor E2-related factor 2 (Nrf2), and subsequently decreased CAT, GPx1, Cu/Zn-SOD and Mn-SOD expression levels. The lowest mRNA levels of interleukin 8 (IL-8) and tumour necrosis factor-alpha (TNF-alpha) were observed in 8.0 g/kg diet, whereas the highest mRNA levels of transforming growth factor-beta (TGF-beta) and interleukin 10 (IL-10) were observed in 8.0 g/kg diet. These results indicated that dietary histidine plays a major role in maintaining intestinal health in juvenile blunt snout bream.