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Author Spotlight: In Vivo Assessment of Thyroid Hormone Disruption Using the THAI Mouse Model
Published on: October 6, 2023
776
Perinatal exposure to environmental chemicals that disrupt thyroid function can perturb testis development
Monica K Draskau1, Ida W Strand1, Raul Ayala Davila2
1National Food Institute, Technical University of Denmark, Kgs. Lyngby, Denmark.
Environmental Pollution (Barking, Essex : 1987)
|October 16, 2024
Summary
Perinatal exposure to the herbicide amitrole or antithyroid drug methimazole (MMI) reduced thyroid hormones (THs) in developing rats. This disruption impaired testis development, affecting germ and Sertoli cells, and raising reproductive health concerns.
Area of Science:
- Endocrinology
- Reproductive Toxicology
- Developmental Biology
Background:
- Thyroid hormones (THs) are critical for mammalian growth and development, particularly impacting skeletal and brain maturation.
- Developmental hypothyroidism can lead to testicular abnormalities, including smaller testes and altered Sertoli cell proliferation.
- Environmental chemicals disrupting thyroid hormone synthesis may pose risks to reproductive health.
Purpose of the Study:
- To investigate the effects of perinatal exposure to the herbicide amitrole and the antithyroid drug methimazole (MMI) on testis development in rats.
- To assess the impact of these exposures on thyroid hormone levels and testicular histology.
- To examine hormonal changes in fetal males following exposure.
Main Methods:
- Pregnant Sprague-Dawley rats were exposed to amitrole (25 or 50 mg/kg/day) or MMI (8 or 16 mg/kg/day) from gestational day 7 until birth, with continued pup exposure via lactating dams until postnatal day 16.
- Thyroid hormone levels were measured on postnatal day 16.
- Testicular parameters, including size and seminiferous tubule diameter, were assessed in pups.
- Fetal male blood hormone levels (progesterone, estradiol) were analyzed.
Main Results:
- Both amitrole and MMI significantly reduced thyroid hormone levels in pups by day 16.
- Perinatal exposure to both agents resulted in smaller testes and reduced seminiferous tubule diameter in 16-day-old pups, indicating disrupted germ and Sertoli cell development.
- Exposure to both chemicals increased fetal male blood progesterone levels.
- Amitrole exposure also led to increased fetal male estradiol levels.
Conclusions:
- Perinatal exposure to amitrole or MMI induces hypothyroidism, adversely affecting male reproductive organ development in rats.
- Environmental chemicals that inhibit thyroid hormone production may disrupt TH-dependent testis development.
- These findings highlight potential risks to human reproductive health from environmental endocrine disruptors.
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