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Considerations when assessing antagonism in vitro: Why standardizing the agonist concentration matters
Peta A Neale1, Frederic D L Leusch1
1Smart Water Research Centre, School of Environment, Griffith University, Southport, QLD 4222, Australia.
Chemosphere
|April 16, 2015
Summary
Standardizing in vitro antagonism assays is crucial. This study recommends using an EC80 concentration for background agonists to improve the reliability of estrogen receptor alpha (ERα), progesterone receptor (PR), and glucocorticoid receptor (GR) antagonism testing.
Area of Science:
- Environmental science
- Endocrinology
- Toxicology
Background:
- Assessing both agonism and antagonism is vital for environmental samples.
- Cell-based in vitro assays can distinguish between agonist and antagonist activity.
- Current in vitro antagonism assessment lacks standardization, with variable competing agonist concentrations.
Purpose of the Study:
- To investigate the impact of varying agonist concentrations on ERα, PR, and GR antagonism assays.
- To determine an optimal background agonist concentration for standardized in vitro antagonism testing.
Main Methods:
- Investigated estrogen receptor alpha (ERα), progesterone receptor (PR), and glucocorticoid receptor (GR) assays in antagonist mode.
- Varied background agonist concentrations to assess their influence on measured antagonistic effects.
- Compared antagonist EC50 values across different background agonist concentrations.
Main Results:
- Antagonistic effects varied by over two orders of magnitude with different agonist concentrations.
- The choice of background agonist concentration significantly impacts assay results.
- An EC80 background agonist concentration was identified as optimal.
Conclusions:
- Standardization of agonist concentration is necessary for reliable in vitro antagonism assays.
- An EC80 background agonist concentration optimizes assay sensitivity and reproducibility.
- This finding is critical for accurate environmental risk assessment of endocrine-disrupting chemicals.
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