Considerations when assessing antagonism in vitro: Why standardizing the agonist concentration matters

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Author(s)
Neale, Peta A
Leusch, Frederic DL
Year published
2015
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There is increasing recognition of the importance of assessing both agonism and antagonism in parallel for environmental samples. Cell-based in vitro assays have the advantage over receptor binding assays as they are able to differentiate between agonist and antagonist activity, but at present there is no standardized approach to assess antagonism in vitro, and in particular the competing agonist concentration can vary in the literature anywhere from half maximal to maximal effect concentrations. In this study, we investigated the influence of changing agonist concentrations in the estrogen receptor alpha (ERα), progesterone ...
View more >There is increasing recognition of the importance of assessing both agonism and antagonism in parallel for environmental samples. Cell-based in vitro assays have the advantage over receptor binding assays as they are able to differentiate between agonist and antagonist activity, but at present there is no standardized approach to assess antagonism in vitro, and in particular the competing agonist concentration can vary in the literature anywhere from half maximal to maximal effect concentrations. In this study, we investigated the influence of changing agonist concentrations in the estrogen receptor alpha (ERα), progesterone receptor (PR) and glucocorticoid receptor (GR) assays run in antagonist mode. The antagonistic effect varied by over two orders of magnitude when using the range of agonist concentrations applied in the literature, clearly indicating the need for standardization. By comparing antagonist EC50 values with different background agonist concentrations, an EC80 background agonist concentration is recommended when assessing antagonism in vitro to optimise both assay sensitivity and reproducibility.
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View more >There is increasing recognition of the importance of assessing both agonism and antagonism in parallel for environmental samples. Cell-based in vitro assays have the advantage over receptor binding assays as they are able to differentiate between agonist and antagonist activity, but at present there is no standardized approach to assess antagonism in vitro, and in particular the competing agonist concentration can vary in the literature anywhere from half maximal to maximal effect concentrations. In this study, we investigated the influence of changing agonist concentrations in the estrogen receptor alpha (ERα), progesterone receptor (PR) and glucocorticoid receptor (GR) assays run in antagonist mode. The antagonistic effect varied by over two orders of magnitude when using the range of agonist concentrations applied in the literature, clearly indicating the need for standardization. By comparing antagonist EC50 values with different background agonist concentrations, an EC80 background agonist concentration is recommended when assessing antagonism in vitro to optimise both assay sensitivity and reproducibility.
View less >
Journal Title
Chemosphere
Volume
135
Copyright Statement
© 2015 Elsevier. Licensed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International (http://creativecommons.org/licenses/by-nc-nd/4.0/) which permits unrestricted, non-commercial use, distribution and reproduction in any medium, providing that the work is properly cited.
Subject
Environmental Monitoring