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Carbaryl, 1-naphthol and 2-naphthol inhibit the beta-1 thyroid hormone receptor-mediated transcription in vitro

Hong Sun1, Ou-Xi Shen, Xiao-Lin Xu

  • 1Key Laboratory of Reproductive Medicine, Institute of Toxicology, Nanjing Medical University, Nanjing, China.

Toxicology
|July 1, 2008
PubMed

Insights

This study developed a reporter gene assay to screen environmental chemicals affecting thyroid hormone receptor (TR) signaling. The assay identified Bisphenol A, Carbaryl, and naphthols as TR antagonists, highlighting potential risks to thyroid function.

Area of Science:

  • Endocrinology
  • Toxicology
  • Molecular Biology

Background:

  • Thyroid hormones (THs) are crucial for mammalian brain development.
  • Environmental chemicals can disrupt THs, impacting health.
  • Thyroid hormone receptor (TR) signaling is a key pathway affected by these disruptions.

Purpose of the Study:

  • To develop and validate a reporter gene assay for screening compounds affecting the TR signaling pathway.
  • To assess the thyroid hormone-disrupting potential of specific environmental chemicals.

Main Methods:

  • A reporter gene assay was established using HepG2 cells transfected with specific vectors (pGal4-L-TRbeta1 and pUAS-tk-Luc).
  • The assay's response to known thyroid hormones (T3 and T4) was characterized.
  • The agonist and antagonist activities of Bisphenol A, Carbaryl, 1-naphthol (1-NAP), and 2-naphthol (2-NAP) were evaluated.

Main Results:

  • The assay demonstrated reliable responses to T3 and T4 with EC50 values of 0.46 nM and 25.53 nM, respectively.
  • Bisphenol A showed weak anti-thyroid hormone activity (IC50 = 6.45 x 10(-5)M).
  • Carbaryl, 1-NAP, and 2-NAP all exhibited TR antagonist activity, with no agonist activity observed.

Conclusions:

  • The developed reporter gene assay is a valuable tool for investigating the effects of environmental chemicals on thyroid function.
  • Industrial chemicals like Carbaryl and naphthols may act as TR antagonists, posing a risk to thyroid hormone signaling.
  • TRs are potential targets for environmental chemical disruption.

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