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Assessment of mercury chloride-induced toxicity and the relevance of P2X7 receptor activation in zebrafish larvae

Cruz, Fernanda Fernandes, Leite, Carlos Eduardo, Pereira, Talita Carneiro Brandão, Bogo, Maurício Reis, Bonan, Carla Denise, Battastini, Ana Maria Oliveira, Campos, Maria Martha, Morrone, Fernanda Bueno
Comparative Biochemistry and Physiology, Part C 2013 v.158 pp. 159-164
Danio rerio, acute effects, acute exposure, additive effect, adenosine triphosphate, antagonists, catalase, heavy metals, larvae, malondialdehyde, mercuric chloride, mercury, models, mortality, oxidative stress, quantitative polymerase chain reaction, receptors, toxicity
Zebrafish (Danio rerio) has been adopted as a model for behavioral, immunological and toxicological studies. Mercury is a toxic heavy metal released into the environment. There is evidence indicating that heavy metals can modulate ionotropic receptors, including the purinergic receptor P2X7. Therefore, this study evaluated the in vivo effects of acute exposure to mercury chloride (HgCl2) in zebrafish larvae and to investigate the involvement of P2X7R in mercury-related toxicity. Larvae survival was evaluated for 24h after exposure to HgCl2, ATP or A740003. The combination of ATP (1mM) and HgCl2 (20μg/L) decreased survival when compared to ATP 1mM. The antagonist A740003 (300 and 500nM) increased the survival time, and reversed the mortality caused by ATP and HgCl2 in association. Quantitative real time PCR showed a decrease of P2X7R expression in the larvae treated with HgCl2 (20μg/L). Evaluating the oxidative stress our results showed decreased CAT (catalase) activity and increased MDA (malondialdehyde) levels. Of note, the combination of ATP with HgCl2 showed an additive effect. This study provides novel evidence on the possible mechanisms underlying the toxicity induced by mercury, indicating that it is able to modulate P2X7R in zebrafish larvae.