Antioxidant responses of the earthworm Lampito mauritii exposed to Pb and Zn contaminated soil

The aim of this study was to provide fundamental data on the biochemical analysis of antioxidant defences in the earthworm exposed to low levels (75, 150, 300 mg kg−1 soil) of Pb and Zn. In order to attain this objective, adult Lampito mauritii were exposed to different doses of Pb and Zn separately for 28 days and the concentrations of oxidized and reduced glutathione, activities of glutathione-S-transferase, glutathione peroxidase and glutathione reductase were assessed. Dose-dependent perturbations were observed in the glutathione–glutathione-S-transferase system and other antioxidant enzymes during the early phase of the exposure to Pb. In the Zn exposed earthworm, the glutathione–glutathione-S-transferase system remained stable and the stimulation of glutathione peroxidase and glutathione reductase activities occurred significantly only on day 14 at 300 mg Zn kg−1. It is concluded that the antioxidants are directly involved in the adaptive response of Lampito mauritii for survival in metal contaminated soil.