Title: Effects of chlorpyrifos on acetylcholinesterase activity in two freshwater fish species (Cnesterodon decemmaculatus and Gambusia affinis)

Authors: Daissy L. Bernal-Rey; Maria Dos Santos Afonso; Renata J. Menendez-Helman

Addresses: Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria Pabellón II 3er Piso, (C1428EHA) Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Ciudad Universitaria Pabellón II 3er Piso, (C1428EHA) Buenos Aires, Argentina ' Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Inorgánica, Analítica y Química Física, Ciudad Universitaria Pabellón II 3er Piso, (C1428EHA) Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Química Física de los Materiales, Medio Ambiente y Energía (INQUIMAE), Ciudad Universitaria Pabellón II 3er Piso, (C1428EHA) Buenos Aires, Argentina ' Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Química Biológica, Ciudad Universitaria Pabellón II 4to Piso, (C1428EHA) Buenos Aires, Argentina; CONICET-Universidad de Buenos Aires, Instituto de Química Biológica de la Facultad de Ciencias Exactas y Naturales (IQUIBICEN), Ciudad Universitaria Pabellón II 4to Piso, (C1428EHA) Buenos Aires, Argentina

Abstract: Chlorpyrifos (CPF) is a widely used organophosphate insecticide. The effect of chlorpyrifos exposure on acetylcholinesterase activity (AChE, biomarker of neurotoxicity) was evaluated in two freshwater fish species (Cnesterodon decemmaculatus and Gambusia affinis). The animals were exposed to sublethal concentrations (1 and 5 µg CPF × L^-1) or remained in control water for 96 h. AChE activity was inhibited 48% and 69% in C. decemmaculatus and 27% and 36% in G. affinis for 1 and 5 µg CPF × L^-1, respectively. In vitro assays showed no differential sensitivity of the enzyme to CPF between species. However, the IC₅₀ for in vitro exposure to chlorpyrifos-oxon (CPF-oxon, a product of the natural oxidative desulfuration of CPF) were 10.2 nM and 54.2 nM for C. decemmaculatus and G. affinis, respectively. Therefore, a different sensitivity of the enzyme between both species could explain the dissimilar behaviour of AChE after in vivo exposure to CPF.

Keywords: chlorpyrifos; pesticides; biomarkers; acetylcholinesterase; AChE; Gambusia affinis; Cnesterodon decemmaculatus; freshwater fish; teleost.

DOI: 10.1504/IJENVH.2017.088113

International Journal of Environment and Health, 2017 Vol.8 No.4, pp.316 - 330

Received: 01 Aug 2016
Accepted: 11 Jan 2017
Published online: 24 Nov 2017 *

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