Repeated exposure to cruciferous allyl nitrile can induce antioxidant and phase 2 detoxification enzymes in various tissues. In the present study, we examined the effect of five days repeated exposure to allyl nitrile at subtoxic levels (0 - 400 μmol/kg/day) on the mouse ear. There was an increase in catalase activity in the ear at 100 - 400 μmol/kg/day, while elevated quinone reductase activity was observed at 400 μmol/kg/day only. Next, after repeated allyl nitrile exposure (0 - 400 μmol/kg/day), the skin irritant croton oil was applied to the ear to induce skin acute inflammation (oedema). Compared with the 0 μmol/kg/day group, animals in the 100 and 400 μmol/kg/day pre-treatment groups showed reduced oedematous response to croton oil. The reduced oedematous response was inversely associated with enhanced myeloperoxidase activity used as index of the presence of neutrophils. These data suggest that repeated exposure to allyl nitrile at subtoxic levels contributes to protection against croton oil-induced ear dermatitis, potentially through decreasing reactive oxygen species and through infiltration of neutrophils.
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