Impact of endocrine disrupters on the synthesis and metabolism of thyroid hormones
Andrea Claudia Freitas Ferreira
Universidade Federal do Rio de Janeiro, Brazi
: Forensic Toxicol Pharmacol 2015, 4:3
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.
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