3 research outputs found
The menace of endocrine disruptors on thyroid hormone physiology and their impact on intrauterine development
The delivery of the appropriate thyroid hormones quantity to target
tissues in euthyroidism is the result of unopposed synthesis, transport,
metabolism, and excretion of these hormones. Thyroid hormones
homeostasis depends on the maintenance of the circulating ‘free’ thyroid
hormone reserves and on the development of a dynamic balance between the
‘free’ hormones reserves and those of the ‘bound’ hormones with the
transport proteins. Disturbance of this hormone system, which is in
constant interaction with other hormone systems, leads to an
adaptational counter-response targeting to re-establish a new
homeostatic equilibrium. An excessive disturbance is likely to result,
however, in hypo- or hyper- thyroid clinical states. Endocrine
disruptors are chemical substances forming part of ‘natural’
contaminating agents found in most ecosystems. There is abundant
evidence that several key components of the thyroid hormones homeostasis
are susceptible to the action of endocrine disruptors. These chemicals
include some chlorinated organic compounds, polycyclic aromatic
hydrocarbons, herbicides, and pharmaceutical agents. Intrauterine
exposure to endocrine disruptors that either mimic or antagonize thyroid
hormones can produce permanent developmental disorders in the structure
and functioning of the brain, leading to behavioral changes. Steroid
receptors are important determinants of the consequences of endocrine
disruptors. Their interaction with thyroid hormones complicates the
effect of endocrine disruptors. The aim of this review is to present the
effect of endocrine disruptors on thyroid hormones physiology and their
potential impact on intrauterine development