Journal of Clinical Toxicology
Open Access

Impact of endocrine disrupters on the synthesis and metabolism of thyroid hormones

4^th Global Summit on Toxicology

August 24-26, 2015 Philadelphia, USA

Andrea Claudia Freitas Ferreira

Posters-Accepted Abstracts: J Clin Toxicol

Abstract :

Endocrine disruptors are compounds able to interfere with the synthesis, transport, effect or metabolism of hormones. Flavonoids
are endocrine disruptors of natural origin, they are polyphenolic compounds produced by plants found in human diet. Although
flavonoids produce many beneficial effects, they have been described to be detrimental to thyroid function. We and others have
described that some flavonoids affect the activity of enzymes important for thyroid homeostasis, such as thyroperoxidase, the key
enzyme for thyroid hormone biosynthesis, and deiodinases, enzymes that convert the prohormone T4 to the metabolically active
hormone T3. Despite that, we have shown that the flavonoid rutin is able to increase thyroid iodide uptake, a feature that could make
this flavonoid useful as adjuvant in radioiodine therapy. It is known that part of the patients with thyroid cancer lose the capacity to
concentrate iodine, due to dedifferentiation of the cancer cells. Thus, a compound able to increase iodide uptake could render these
cells susceptible to radioiodine therapy. Synthetic endocrine disruptors include plasticizers, such as bisphenol A and phthalates,
which have been described to act as obesogens. Thyroid hormones are the main regulators of basal metabolic rate, thus a disruption
in the synthesis or metabolism of thyroid hormones could predispose the individual to gain weight. In fact, we have found that some
plasticizers are able to inhibit deiodinase activity. Therefore, the reduced production of T3 locally in target tissues could contribute to
decrease the metabolic rate and thus might contribute to the increment in the prevalence of obesity.