Thyroid disruption by low-dose BDE-47 in prenatally exposed lambs

Area of Science:

• Environmental Toxicology
• Endocrinology
• Developmental Biology

Background:

• Polybrominated diphenyl ethers (PBDEs) are persistent organic pollutants found globally.
• Human exposure levels to PBDEs are a growing public health concern.
• The impact of low-dose prenatal PBDE exposure on thyroid function requires further investigation.

Purpose of the Study:

• To assess the effects of environmentally relevant PBDE levels on thyroid status in pregnant sheep and their offspring.
• To determine if prenatal exposure to BDE-47 affects thyroid hormones in developing lambs.
• To investigate PBDE accumulation in fetal tissues following maternal exposure.

Main Methods:

• Pregnant sheep were intravenously administered weekly doses of BDE-47 (0.2, 2, or 20 microg/kg b.w.) from week 5 to 15 of gestation.
• Control groups received vehicle injections.
• Thyroid hormone levels (T4, T3) and BDE-47 concentrations were measured in blood and adipose tissue of ewes and lambs.

Main Results:

• A significant reduction in total thyroxine (T4) and triiodothyronine (T3) was observed in lambs exposed prenatally to BDE-47.
• No significant alterations in thyroid hormone levels were detected in the pregnant sheep.
• PBDE-47 was detected in the adipose tissue of exposed lambs, indicating fetal accumulation.

Conclusions:

• Prenatal exposure to low-dose PBDEs can lead to the accumulation of these compounds in the offspring's fat.
• Developing fetuses are susceptible to PBDE-induced disruption of thyroid hormone metabolism.
• These findings highlight potential risks of environmental PBDE exposure to fetal development and thyroid homeostasis.