title: Phenylthiourea disrupts thyroid function in developing zebrafish.
abstract: Thyroid hormone (T4) can be detected in thyroid follicles in wild-type zebrafish larvae from 3 days of development, when the thyroid has differentiated. In contrast, embryos or larvae treated with goitrogens (substances such as methimazole, potassium percholorate, and 6-n-propyl-2-thiouracil) are devoid of thyroid hormone immunoreactivity. Phenythiourea (PTurea; also commonly known as PTU) is widely used in zebrafish research to suppress pigmentation in developing embryos/fry. PTurea contains a thiocarbamide group that is responsible for goitrogenic activity in methimazole and 6-n-propyl-2-thiouracil. In the present study, we show that commonly used doses of 0.003% PTurea abolish T4 immunoreactivity of the thyroid follicles of zebrafish larvae. As development of the thyroid gland is not affected, these data suggest that PTurea blocks thyroid hormone production. Like other goitrogens, PTurea causes delayed hatching, retardation and malformation of embryos or larvae with increasing doses. At doses of 0.003% PTurea, however, toxic side effects seem to be at a minimum, and the maternal contribution of the hormone might compensate for compromised thyroid function during the first days of development.
authors.affiliation: Institute for Developmental Biology, University of Cologne, Gyrhofstrasse 17, 50923 Cologne, Germany.
authors.forename: Osama A
authors.initials: OA
authors.lastname: Elsalini
authors.forename: Klaus B
authors.initials: KB
authors.lastname: Rohr
mesh_terms: D000818:Animals; D013956:Antithyroid Agents / Q000494:pharmacology*; D008675:Metamorphosis, Biological; D008713:Methimazole / Q000494:pharmacology; D009154:Mutation; D010472:Perchlorates / Q000494:pharmacology; D010670:Phenylthiourea / Q000494:pharmacology*; D017680:Potassium Compounds / Q000494:pharmacology; D011441:Propylthiouracil / Q000494:pharmacology; D013961:Thyroid Gland / Q000187:drug effects* / Q000196:embryology / Q000378:metabolism*; D013963:Thyroid Hormones / Q000494:pharmacology; D015027:Zebrafish / Q000196:embryology* / Q000254:growth & development
chemical_list: D013956:Antithyroid Agents; D010472:Perchlorates; D017680:Potassium Compounds; D013963:Thyroid Hormones; C009006:potassium perchlorate; D008713:Methimazole; D010670:Phenylthiourea; D011441:Propylthiouracil