Oxidative damage repair by glutamine in fish enterocytes

Fish intestine is very sensitive to oxidative damage. Repair of damaged enterocytes may be involved to restore normal function of fish intestine. However, studies of fish enterocyte repair are scarce. The present study aimed to investigate the potential repair role of glutamine after a H₂O₂ challenge. In this study, fish enterocytes were post-treated with graded levels of glutamine (0, 4, 8, 12 and 20 mM of glutamine) after expose to 100 μM H₂O₂. The basal control cells were kept in the glutamine-free minimum essential medium only. Results showed that the H₂O₂-induced decreases in 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide optical density, alkaline phosphatase and Na⁺, K⁺-ATPase activities were completely restored by subsequent glutamine treatments. In addition, cellular injury (lactate dehydrogenase), lipid peroxidation (malondialdehyde) and protein oxidation (protein carbonyls) caused by H₂O₂ were reversed by subsequent glutamine treatments. Furthermore, the H₂O₂-induced decreases in glutathione contents, glutathione reductase, superoxide dismutase and glutathione peroxidase activities were completely restored by subsequent glutamine treatments. In summary, the present study indicated that glutamine improved the repair activity in fish enterocytes after challenge with H₂O₂.