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World Journal of Thyroid Research Updates

World Journal of Thyroid Research Updates - Volume 1

Thyroid Gland as a Target for Endocrine Chemical Disruptors

Published on: 11 December 2015

Pages: 1-4

Patricia de Campos1, Isabela Medeiros de Oliveira1, Claudio Alvarenga Oliveira2, Marco Aurelio Romano1 and Renata Marino Romano1

 1Laboratory of Reproductive Toxicology, Department of Pharmacy, State University of Centro-Oeste, Rua Simeao Camargo Varela de Sa, 03, Zip-Code 85040-080, Parana, Brazil; 2Department of Animal Reproduction, Faculty of Veterinary Medicine, University of Sao Paulo, Av. Prof. Dr. Orlando Marques de Paiva, 87, Zip-Code 05508-270, Sao Paulo, Brazil

Abstract: Endocrine chemical disruptors (ECDs) are exogenous substances that may interfere with synthesis, secretion, transport, bind or metabolism of natural hormones in the organism. The aim of this review was to position the thyroid gland as a target of electrophiles toxicants. The thyroid demonstrated to be disrupted by polychlorinated biphenyls (PCBs), polybrominated diphenyl ethers (PBDEs), phthalates, perchlorate, organochlorines, dioxins, bisphenol A (BPA) flame-retardants, pesticides, polycyclic aromatic hydrocarbons (PAHs), and phytoestrogens. Regarding the chemical structure, many toxicants are electron deficient (electrophiles) that form covalent bonds with cognate electron rich (nucleophilic) sites on biological targets, promoting the toxic effects. Almost all ECDs recognized to interfere with thyroid hormone (THs) are electrophile and have hydrogen bond acceptor (HBA) sites in their chemical structure. Thyroid hormone production by the thyroid gland depends on H2O2 generated by NADPH oxidases, and this reaction releases nucleophiles and electrophiles in the thyrocyte cytoplasm. Therefore, evidences suggest the interaction of electrophiles toxicants with nucleophiles from oxidative reactions in thyrocytes, which may compromise the thyroid gland function.

Keywords: Endocrine chemical disruptors, Reactive oxygen species, Electrophile toxicants, Thyroid hormone synthesis, Thyroid dysfunction.

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