Comparative study of diclofenac-induced embryotoxicity and teratogenesis in Xenopus laevis and Lithobates catesbeianus, using the frog embryo teratogenesis assay: Xenopus (FETAX)

Abstract

Water is an increasingly deteriorated, limited natural resource due to population increase and industrialization. Also, the widespread use of pharmaceuticals in modern society leads to their presence in domestic, hospital and industrial effluents. Due to their analgesic properties, some of the most commonly used pharmaceuticals are non- steroidal anti-inflammatory drugs (NSAIDs). High concentrations of one these products, diclofenac (DCF), have been detected in effluents and water bodies of different countries, including Mexico. Diverse studies show that trace amounts (ng L−1 to μg L−1) of this compound induce toxicity on aquatic organisms such as algae, microcrustaceans and fish. However, studies on its potential toxicity during development in species of commer- cial interest such as the American bullfrog Lithobates catesbeianus are scarce. The present study aimed to evaluate DCF-induced teratogenesis and embryotoxicity in Xenopus laevis and L. catesbeianus, a species marketed as a nutritional meat source in Mexico, using the frog embryo teratogenesis assay: Xenopus (FETAX). Oocytes in mid-blastula transition were exposed for 96 h to 1, 4, 8, 16, 32 and 62.5 mg DCF L−1. The criteria evaluated were mortality, malformation and growth inhibition. The teratogenic index was 4.2 in L. catesbeianus, three fold higher than the reference limit (1.5), and 3.9 in X. laevis. Diclofenac induced diverse malformations in both species, the most frequent of these being axial malformations in the tail and notochord, edema and stunted growth. Results indicate that DCF is a potentially teratogenic compound and is toxic during development in X. laevis and L. catesbeianus, a species which, due to its sensitivity, can be used to evaluate the toxicity of pharma- ceutical products, using FETAX.