Avaliação dos efeitos tóxicos da peçonha de Bothrops jararacussu sobre embriões e larvas de peixe-zebra (Danio rerio)

Abstract

Ophidism is a neglected disease responsible for affecting approximately 2.7 million people worldwide, mainly affecting tropical and subtropical countries. In Brazil, 90% of the reported and identified cases of these accidents are caused by snakes of the Bothrops genus. Bothrops jararacussu has clinical relevance, and its venom is composed of substances capable of triggering local and systemic effects, culminating in the development of morbidities and/or mortality in the affected individual. The present study aimed to evaluate the toxic effects triggered by the presence of the venom on the zebrafish embryo and larvae model system. The stability of B. jararacussu venom under the conditions used in the toxicity experiments in zebrafish embryos and larvae was evaluated by measuring the prothrombin and activated partial thromboplastin times of citrated human plasma in the presence of different amounts of the venom and in different exposure times. In addition, the mortality rate, morphological alterations, spontaneous movements and heart beats of embryos were evaluated, as well as certain parameters of toxicity and alterations in the biochemical profile of the biomarker enzymes of toxicity (glutathione-S-transferase, catalase, lactate dehydrogenase, and acetylcholinesterase) of zebrafish larvae after exposure to B. jararacussu venom. Acute toxicity was assessed by semi-static exposure of zebrafish embryos and larvae to the venom for 96 hours. Our results indicated that B. jararacussu venom causes toxicity in zebrafish embryos and larvae, causing embryo mortality in the first 24 hours of exposure, in addition to altering the number of spontaneous tail movements and acetylcholinesterase activity. Changes in the activities of the other antioxidant enzymes evaluated were also verified. The evaluation of these results allows us to suggest that the toxic effects caused by the presence of the venom in the early stages of zebrafish development are mediated, by neurotoxic action, induction of oxidative and metabolic stress possibly caused by low molecular weight components and/or proteins that makes up the venom. Toxinological evaluations using zebrafish as a model are scarce, however, this study presented promising results that encouraged the development of future research in snake toxinology using this animal as a model organism.