Short-term responses to cadmium exposure in the estuarine polychaete Laeonereis acuta (polychaeta, Nereididae): subcellular distribution and oxidative stress generation.

Some effects of cadmium exposure (100 microg/L for 4, 8, 12, and 24 h) on the estuarine polychaete Laeonereis acuta (Nereididae) were evaluated. This polychaete was able to accumulate cadmium in the body, with the metal stored mainly in the cytosolic fraction (>10 kDa). Activity of the antioxidant enzymes superoxide dismutase, glutathione S-transferase, and glutathione reductase (GR) as well as the total oxyradical scavenger capacity, the glutamate cysteine ligase catalytic subunit gene expression, and the metallothionein-like proteins content were not affected by cadmium at any exposure time tested. Catalase (CAT) activity, however, was significantly lower (p < 0.05) in worms treated with cadmium compared with that in controls after 8 h of exposure. At the same exposure time, lipid peroxide levels were increased (p < 0.05) in worms exposed to cadmium compared with those in control worms. Interestingly, CAT and GR activities decreased over time (p < 0.05) independent of cadmium treatment, which is a result that could be attributed to starvation. The effects caused by cadmium in the present study were observed only after 8 h of exposure, demonstrating that cadmium can generate oxidative stress.