title: Comparative effect of pesticides on brain acetylcholinesterase in tropical fish.
abstract: Monitoring of pesticides based on acetylcholinesterase (AChE; EC 3.1.1.7) inhibition in vitro avoids interference of detoxification defenses and bioactivation of some of those compounds in non-target tissues. Moreover, environmental temperature, age and stress are able to affect specific enzyme activities when performing in vivo studies. Few comparative studies have investigated the inter-specific differences in AChE activity in fish. Screening studies allow choosing the suitable species as source of AChE to detect pesticides in a given situation. Brain AChE from the tropical fish: pirarucu (Arapaima gigas), cobia (Rachycentron canadum) and Nile tilapia (Oreochromis niloticus) were characterized and their activities were assayed in the presence of pesticides (the organophosphates: dichlorvos, diazinon, chlorpyrifos, temephos, tetraethyl pyrophosphate- TEPP and the carbamates: carbaryl and carbofuran). Inhibition parameters (IC₅₀ and Ki) for each species were found and compared with commercial AChE from electric eel (Electrophorus electricus). Optimal pH and temperature were found to be 8.0 and 35-45 °C, respectively. A. gigas AChE retained 81% of the activity after incubation at 50 °C for 30 min. The electric eel enzyme was more sensitive to the compounds (mainly carbofuran, IC₅₀ of 5 nM), excepting the one from A. gigas (IC₅₀ of 9 nM) under TEPP inhibition. These results show comparable sensitivity between purified and non-purified enzymes suggesting them as biomarkers for organophosphorus and carbamate detection in routine environmental and food monitoring programs for pesticides.
authors.affiliation: Laboratório de Imunopatologia Keizo Asami-LIKA and Laboratório de Enzimologia-LABENZ, Departamento de Bioquímica, Universidade Federal de Pernambuco, Recife-PE, Brazil.
authors.forename: Caio Rodrigo Dias
authors.initials: CR
authors.lastname: Assis
authors.forename: Amanda Guedes
authors.initials: AG
authors.lastname: Linhares
authors.forename: Vagne Melo
authors.initials: VM
authors.lastname: Oliveira
authors.forename: Renata Cristina Penha
authors.initials: RC
authors.lastname: França
authors.forename: Elba Veronica Matoso Maciel
authors.initials: EV
authors.lastname: Carvalho
authors.forename: Ranilson Souza
authors.initials: RS
authors.lastname: Bezerra
authors.forename: Luiz Bezerra
authors.initials: LB
authors.lastname: de Carvalho
mesh_terms: D000110:Acetylcholinesterase / Q000378:metabolism*; D000818:Animals; D015415:Biomarkers / Q000378:metabolism; D001921:Brain / Q000187:drug effects / Q000201:enzymology*; D002219:Carbamates / Q000633:toxicity*; D004784:Environmental Monitoring; D005399:Fishes / Q000378:metabolism*; D010755:Organophosphates / Q000633:toxicity*; D010575:Pesticides / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity
chemical_list: D015415:Biomarkers; D002219:Carbamates; D010755:Organophosphates; D010575:Pesticides; D014874:Water Pollutants, Chemical; D000110:Acetylcholinesterase