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Updated: Aug 29, 2026
In vivo Characterization of Endocrine Disrupting Chemical Effects via Thyroid Hormone Action Indicator Mouse
Published on: October 6, 2023
In vitro assay of thyroid disruptors affecting TSH-stimulated adenylate cyclase activity
F Santini1, P Vitti, G Ceccarini
1Department of Endocrinology, Centro di Eccellenza AmbiSEN, University of Pisa, Pisa, Italy. fsantini@endoc.med.unipi.it
Abstract:
Several natural or synthetic chemicals have been indicated as potential thyroid disruptors. The development of in vitro assays has been recommended to comprehensively assess the potential thyroid disrupting activity of a substance or a complex mixture. In this study, 12 substances suspected for acting as thyroid disruptors were tested for their ability to inhibit TSH-stimulated cAMP production in vitro. Those substances producing an inhibition were further studied to establish the level at which they interfere with this step of thyroid cell function. Using Chinese hamster ovary cells (CHO) transfected with the recombinant human TSH receptor, a dose-dependent inhibition of TSH-stimulated adenylate cyclase activity was produced by 1,1-bis-(4-chlorphenyl)-2,2,2-trichloroethan (DDT), Aroclor 1254 and Melissa Officinalis. All three substances also inhibited the cAMP production stimulated by TSH receptor antibody. Melissa Officinalis produced a significant inhibition of TSH binding to its receptor and of antibody binding to TSH, while no significant changes were produced by Aroclor 1254 or DDT in these assays. These data suggest that principles contained in Melissa Officinalis may block the binding of TSH to its receptor by acting both on the hormone and the receptor itself, while DDT and Aroclor 1254 affect cAMP production mainly at post-receptor step. In conclusion, we have developed a set of in vitro assays that allow investigation into the effect of thyroid disruptors on the TSH-mediated activation of the cAMP cascade. These assays may be useful to identify the mechanism of action of thyroid disruptors, coming beside and supporting animal studies or epidemiological surveys.
Insights
This study developed in vitro assays to identify thyroid disruptors. Melissa Officinalis, DDT, and Aroclor 1254 were found to inhibit TSH-stimulated cAMP production through different mechanisms.
Area of Science:
- Endocrinology
- Toxicology
- Cell Biology
Background:
- Chemicals can disrupt thyroid function, necessitating reliable testing methods.
- In vitro assays are crucial for assessing thyroid-disrupting potential.
- 12 suspected thyroid disruptors were evaluated for their impact on TSH-stimulated cAMP production.
Purpose of the Study:
- To develop and utilize in vitro assays to investigate thyroid disruptor mechanisms.
- To determine how specific chemicals interfere with TSH-mediated cAMP signaling.
- To differentiate between pre-receptor and post-receptor mechanisms of action.
Main Methods:
- Utilized Chinese hamster ovary (CHO) cells transfected with the human TSH receptor.
- Assessed inhibition of TSH-stimulated cAMP production and adenylate cyclase activity.
- Investigated TSH binding to its receptor and antibody binding to TSH.
Main Results:
- DDT, Aroclor 1254, and Melissa Officinalis inhibited TSH-stimulated cAMP production.
- Melissa Officinalis inhibited TSH binding and antibody binding to TSH.
- DDT and Aroclor 1254 primarily affected post-receptor signaling pathways.
Conclusions:
- Developed in vitro assays to analyze thyroid disruptor effects on the cAMP cascade.
- Identified distinct mechanisms of action for Melissa Officinalis, DDT, and Aroclor 1254.
- These assays support animal and epidemiological studies in thyroid disruptor research.
