Oxidative stress induced by acute and sub-chronic cadmium exposure in the ovaries of the freshwater crab Sinopotamon henanense (Dai, 1975)

Abstract

Cadmium (Cd) is one of the most toxic environmental pollutants, and is known to have multiple toxic effects on many tissues and organs, including the ovaries. However, the mechanisms underlying Cd toxicity on animal ovaries remain unknown. Here we examined the acute and sub-chronic effects of Cd on the ovaries of the freshwater crab,Sinopotamon henanense(Dai, 1975). Acute effects were studied by treating crabs for 3, 5 and 7 days with two Cd concentrations (7.25 or 14.5 mg/l) and sub-chronic Cd treatment was achieved by treating crabs for 7, 14 and 28 days, respectively, with 0.725 or 1.45 mg/l of Cd. Results showed that Cd levels were significantly increased, in both dose- and time-dependent manners in the sub-chronic groups and in a dose-dependent manner in the acute groups. In the sub-chronic groups, the activities of antioxidant enzymes, SOD, CAT and GPx, initially decreased at day 7 or 14, and increased after 14 and/or 28 days, which was accompanied by an increase in malondialdehyde (MDA) and metallothionein (MT) levels. In the acute groups, there were no statistically significant changes in the activities of the antioxidant enzymes nor in the levels of MDA and MT. To conclude, our results suggest that Cd may do more oxidative damage to cells of crab ovaries at sub-chronic exposure than at acute exposure, which is due to Cd-induced oxidative stress.