A comparative study of acetylcholinesterase and general-esterase activity assays using different substrates, in vitro and in vivo exposures and model organisms.

Autor: Cao Y; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Denmark. Electronic address: y.cao@plen.ku.dk., Herrero-Nogareda L; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Denmark. Electronic address: laia@plen.ku.dk., Cedergreen N; Department of Plant and Environmental Sciences, University of Copenhagen, Thorvaldsensvej 40, 1871, Frederiksberg, Denmark. Electronic address: ncf@plen.ku.dk.
Jazyk: angličtina
Zdroj: Ecotoxicology and environmental safety [Ecotoxicol Environ Saf] 2020 Feb; Vol. 189, pp. 109954. Date of Electronic Publication: 2019 Nov 20.
DOI: 10.1016/j.ecoenv.2019.109954
Abstrakt: Acetylcholinesterase (AChE) and general-esterase (GE) activities are important to understand detoxification processes of xenobiotics. The assays to quantify them have employed different substrates, inhibitors, types of experiments (in vitro and in vivo) and model organisms. The aim of this work was to give a systematic overview of the effect of the above factors on the outcome of AChE and GE activity measurements. We showed that AChE activity could be measured with the substrate acetylthiocholine iodide (AChI) but not with acetylcholine bromide (AChB) and only in in vitro assays. For GE activity, Michaelis-Menten kinetics differed between the substrates 4-methylumbellifery butyrate (4-MUB) and 1-naphtyl acetate (1-NA) in the measurements of in vitro activity, but their inhibition curves and IC 50 values for the general inhibitor tetraisopropyl pyrophosphoramide (iso-OMPA) were similar, confirming that both substrates targeted the same group of enzymes. The GE substrate 4-MUB was applicable both in vitro and in vivo, while 1-NA was only applicable in vitro due to its high acute toxicity. When comparing the zooplankton crustacean Daphnia magna and the sediment dwelling Chironomus riparius, the latter had a four-fold higher maximal AChE activity (V max ) and a higher susceptibility to the AChE inhibitor BW284c51 (four-fold lower 50% inhibitory concentration, IC 50 ), but a lower maximal GE activity and lower susceptibility to iso-OMPA (higher IC 50 ), indicating significant species differences between in C. riparius and D. magna. We conclude that both choice of substrate and exposure method matters for the outcome of esterase assays and that esterase compositions between species may vary significantly.
(Copyright © 2019 Elsevier Inc. All rights reserved.)
Databáze: MEDLINE
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