Comparative teratogenicity of Chlorpyrifos and Malathion on Xenopus laevis development.

摘要

The embryotoxic potential of chlorpyrifos (CPF) and malathion (MTN) was evaluated by modified Frog Embryo Teratogenesis Assay-Xenopus (FETAX). CPF and MTN were not embryolethal even at the highest concentration tested (6000 micro g/litre), but both exhibited a powerful teratogenicity. The probit analysis of malformed larva percentages showed a TC50 of 161.54 micro g/litre for CPF, and a TC50 of 2394.01 micro g/litre for MTN. Therefore, CPF teratogenicity was approximately 15 times higher than MTN. Larvae of both exposed groups were mainly affected by ventral and/or lateral tail flexure coupled with abnormal gut coiling. Histopathological diagnosis displayed abnormal myotomes and myocytes with marked hypertrophies localized at the cell extremity, probably due to a breakaway of myofibril extremities at the intersomitic junction level. We speculate that this muscular damage was related to inhibition of acetylcholinesterase that showed a clear concentration-response in CPF and MTN exposed larvae. The teratogenic effects of these anticholinesterase compounds on Xenopus laevis myogenesis suggest a possible role played by organophosphorus pesticides on induction of congenital muscular dystrophy.