Mixture effect of two antifungal triazoles (triadimefon and cyproconazole) in rat and Amphibian embryos cultured in vitro

The present work aims to evaluate the teratogenic potential of two triazole-derived fungicides (triadimefon, FON, cyproconazole, CYPRO) alone, as well as their action in a mixed solution on Amphibian (Xenopus laevis) and rat embryos cultured in vitro. On the basis of the morphological and molecular interclasses similarities at the phylotypic stage, low vertebrate animal models have been proposed as alternative to mammals in assessing the developmental toxicity of xenobiotics. Triazole derivatives represent a large class of molecules with antifungal properties, used in agriculture and human-veterinary therapy. Experimental studies indicate all the tested triazoles as teratogenic in rodents, rabbits, amphibians and tunicates, and neurulation as the most sensitive period for inducing craniofacial defects thus affecting the organization of embryonic transient structures (branchial arches). Rat embryos were exposed during the whole culture period (from early neurulation till phylotypic stage) to 7.8–250Mof two agrochemical triazoles (FON and CYPRO) alone, or to their mixture (MIX1: FON 7.8M plus CYPRO 7.8M). At the end of the culture period embryos were morphologically examined and immunostained to evaluate neural crest cell migration. X. laevis embryos were exposed during early neurulation stages to FON and CYPRO alone (3.9-250M), to MIX1, and to MIX2 (FON 3.9M plus CYPRO 3.9M). At the end of the exposures, embryos were washed and allowed to reach the phylotypic stage or the larval stage 47 to evaluate neural crest cell migration and craniofacial morphology. The obtained results confirmFONand CYPRO as teratogenic and showed a clear mixture effect in both species. This suggests that the teratogenic mechanism is common for the two molecules and that it is able to act in different Vertebrate species, indicating X. laevis as an adequate alternative animal model for teratogenic screening of mixtures obtained from molecules of this chemical class.