Role of reactive oxygen species in expulsion ofNippostrongylus brasiliensisfrom rats

Abstract

SUMMARYTo understand the mechanism for the expulsion ofNippostrongylus brasiliensisfrom rats, age-dependent variations in the metabolism of reactive oxygen species in the parasite and the host intestines were examined.N. brasiliensisshowed an age-dependent increase in its susceptibility to xanthine-xanthine oxidase andt−butyl hydroperoxide generated oxidants as well as to H2O2. Protection obtained with several scavengers suggested that the worms were damaged by the combined action of oxidants generated by thein vitrosystems employed. The level of superoxide dismutase in the nematode and its release into the surroundings exhibited a marked depression with advancement of age. No such alteration was, however, recorded for catalase and glutathione peroxidase. An appreciable decrease in the level of reduced glutathione in olderN. brasiliensisappears to render them prone to oxidant attack. The rat intestines, on the other hand, exhibited an appreciable depression in catalase and a reduced glutathione content with progress of the infection. Vitamin E levels were elevated. The release of O27and H2O2by the intestines was also found to be greater during later stages of the infection. The combined effect of the changes observed inN. brasiliensisand in the rat intestines may be at least partly responsible for expulsion of the nematode from the rats after day 10.