Increase in thioredoxin activity of intestinal epithelial cells mediated by oxidative stress

Hydrogen peroxide was cytotoxic to the small intestine epithelial cell line , IEC-6, as judged from an MTT assay and the release of lactate dehydrogena se. The glutathione S-transferase and thioredoxin reductase activities and SW content decreased dose-dependently with H2O2, but thioredoxin activity i ncreased at low H2O2 concentrations. In addition, the increase in thioredox in activity was time-dependent during the initial stages of oxidative stres s, A reverse transcription-polymerase chain reaction (RT-PCR) amplification also showed that the mRNA content in IEC-6 cells increased time-dependentl y at 0.25 mM H2O2. These results indicate that cellular oxidative shock cau ses an increase in the activity of thioredoxin, which is involved in the de fense mechanism against oxidative stress.