Effects of glutamine on hydrogen peroxide-induced oxidative damage in intestinal epithelial cells of Jian carp (Cyprinus carpio var. Jian)
2009
Chen, Jin | Zhou, Xiao-qiu | Feng, Lin | Liu, Yang | Jiang, Jun
The present study explored the effects of glutamine on hydrogen peroxide (H₂O₂)-induced oxidative stress in isolated carp enterocytes. In order to select an optimal H₂O₂ concentration to induce oxidative stress in enterocytes, cultures were treated with different concentrations of H₂O₂ (0-100 μM) for 16 h. The results showed that exposure to H₂O₂ increased lactate dehydrogenase activity and malondialdehyde levels in a dose-dependent manner in the culture medium, suggesting increase toxicity of H₂O₂. Thus, 100 μM was an appropriate concentration for inducing oxidative stress. We then examined the cytoprotective effects of glutamine under conditions of oxidative stress. Cells were treated with glutamine (0-20 mM) in the presence of H₂O₂ (100 μM) for 16 h. The control cells were kept in the glutamine-free MEM only. Results showed that glutamine completely blocked H₂O₂-stimulated release of lactate dehydrogenase. Furthermore, glutamine reduced H₂O₂-induced increase in malondialdehyde level and protein carbonyls content to the level seen in the control culture. In addition, glutamine treatment completely prevented the decrease in Na⁺-K⁺-ATPase, superoxide dismutase, catalase, glutathione peroxidase, glutathione reductase, glutathione S-transferase activities as well as reduced glutathione concentration and the ratio between reduced and oxidized glutathione induced by H₂O₂. No significant difference was observed between cells incubated with glutamine in the presence of H₂O₂ and control cells in values for most of the markers mentioned above. Complete protection was obtained at a concentration of glutamine as small as 4 mM. The present results indicate that glutamine is effective in protecting against H₂O₂-induced oxidative stress in carp intestinal epithelial cells.
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