Effects of glutamine on hydrogen peroxide-induced oxidative damage in intestinal epithelial cells of Jian carp (Cyprinus carpio var. Jian)

摘要

The present study explored the effects of glutamine on hydrogen peroxide (HO)-induced oxidative stress in isolated carp enterocytes. In order to select an optimal HO concentration to induce oxidative stress in enterocytes, cultures were treated with different concentrations of HO (0-100 oM) for 16 h. The results showed that exposure to HO increased lactate dehydrogenase activity and malondialdehyde levels in a dose-dependent manner in the culture medium, suggesting increase toxicity of HO. Thus, 100 oM 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 HO (100 oM) for 16 h. The control cells were kept in the glutamine-free MEM only. Results showed that glutamine completely blocked HO-stimulated release of lactate dehydrogenase. Furthermore, glutamine reduced HO-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 HO. No significant difference was observed between cells incubated with glutamine in the presence of HO 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 HO-induced oxidative stress in carp intestinal epithelial cells.