Disruption of Thyroid Hormone Function by Environmental Pollutants

Abstract

A great number of synthetic chemicals are released into the environment, many of which are known or thought to interfere with normal thyroid hormone (TH) function. THs play important roles in regulating growth and development and maintaining metabolic homeostasis. For example, amphibian tadpole metamorphosis is a TH-triggered and controlled developmental process, and has proven to be useful as a screening tool for environmental pollutants suspected of disrupting TH functions. TH disruption is thought to be caused through a variety of mechanisms, including increased thyroxine (T₄) metabolism by uridine diphosphate glucuronyl transferases (UDPGTs), blocking TH signaling through TH receptors (TRs), and induction of mitochondrial membrane permeability transition (MPT). As our knowledge concerning the specific effects of these chemicals is very limited, further research is needed to obtain accurate information to be used in establishing guidelines for the protection of health in humans and wildlife.