Involvement of apoptosis in malathion-induced cytotoxicity in a grass carp (Ctenopharyngodon idellus) cell line

We investigated the role of apoptosis in malathion-induced cytotoxicity in the grass carp (Ctenopharyngodon idellus) cell line ZC-7901. Fish cells were treated with different concentrations of malathion (0.62-95 mg/L), and the IC50 ranged from 37.94 +/- 1.93 mg/L for 12 h to 3.04 +/- 0.27 mg/L for 72 h by the MTT assay. Apoptosis was detected by confocal laser scanning microscopy, transmission electron microscopy, TUNEL reaction, DNA laddering and a flow cytometric PI staining assay. The results demonstrated that apoptosis was involved in the cytotoxic effect of malathion, and that malathion-induced apoptosis occurred in a dose- and time-dependent manner. In addition, the induction of apoptosis by malathion was accompanied by mitochondrial membrane potential (Delta Psi(m)) disruption, intracellular Ca2+ elevation, generation of reactive oxygen species (ROS) and ATP depletion. Our investigation suggested that malathion exerts its cytotoxic effects by the induction of apoptosis via a direct effect on the mitochondria. (c) 2005 Elsevier Inc. All rights reserved.