A simple short term method to study thyroid disruption using a fetal rat thyroid culture

Area of Science:

• Endocrinology
• Toxicology
• Developmental Biology

Background:

• Investigating thyroid modulation activity of numerous chemicals is limited by ethical and financial constraints of in vivo studies.
• An in vitro mechanism-based strategy is proposed as a more suitable approach for identifying thyroid hormone disrupting chemicals.
• This study introduces a novel, cost-effective short-term culture assay for thyroid disruption evaluation.

Purpose of the Study:

• To develop and validate a simple, inexpensive in vitro short-term culture assay for studying thyroid disruption.
• To assess the viability and function of cultured fetal thyroid glands over a 24-hour period.
• To determine the assay's capability in reproducing in vivo responses to thyroid modulators.

Main Methods:

• Fetal thyroid glands (gestation day 20.5) were cultured for up to 24 hours.
• Explant viability was assessed using the MTT assay.
• Thyroid stimulating hormone (TSH) and 6-propyl-2-thiouracil (PTU) were used to modulate thyroid function, with assessments via morphometrical analysis and immunohistochemistry for thyroxine expression.

Main Results:

• Thyroid gland viability and metabolic activity increased with culture time, peaking at 24 hours.
• Follicular epithelial cells showed a concentration-dependent response to thyrotropin.
• TSH treatment significantly induced thyroxine expression, while PTU inhibited it, consistent with in vivo effects.

Conclusions:

• Cultured GD20.5 fetal thyroids maintain viability and function for up to 24 hours under simple laboratory conditions.
• This in vitro assay successfully reproduces in vivo responses to thyroid modulators.
• The developed short-term culture assay is a suitable method for studying the mechanisms of thyroid disruption.