Propylthiouracil

About: Propylthiouracil is a research topic. Over the lifetime, 2181 publications have been published within this topic receiving 46996 citations. The topic is also known as: Thyreostat® & 2,3-dihydro-6-propyl-2-thioxo-4(1H)-pyrimidinone.

Otic Lesions and Congenital Hypothyroidism in the Developing Chick

Abstract: In an effort to elucidate the relation, if any, between thyroid abnormality and congenital deafness in Pendred's syndrome, an experiment was designed to study the effects of hypothyroidism on middle and inner ear hearing structures, including the auditory nerve and its central projection, in developing chick embryos. Propylthiouracil (PTU), 2 mg, was injected into the albumin of fertile chick eggs on the 10th incubation day. Single doses of L-thyroxine (range 1-100μg) were inoculated in a similar manner, either alone or with PTU. Control inocula included sterile saline or water. After hatching, each chick was examined for obvious malformations. The thyroid glands, middle and inner ear mechanisms, auditory nerve, and brainstem were studied grossly and with different histologic staining techniques. When compared to controls, chicks exposed to PTU on their 10th incubation day exhibited: increased mortality, delayed hatching, reduced size, incomplete yolk sac absorption, and death within 5 days unless exogenous thyroid hormone was provided in the first 24-48 hr after hatching. Specific, consistent, morphologic alterations were observed in their thyroid glands as well as in the sensory hair cells of the acoustic papilla and cells of the spiral ganglion of the cochlea. Our data also indicate that if 50-75 μg of L-thyroxine is given simultaneously with (or as long as 120 hr after) the PTU injection on the 10th incubation day, one cannot detect the gross defects, marked thyroid lesions, or abnormal histology in cells of the cochlea and its ganglion. A relationship between embryonic thyroid gland function and the hearing mechanism of the chick embryo is suggested.

Chemically Induced Mammary Cancer in Rats with Altered Thyroid Function

Abstract: The administration of thyroxin at a dosage of 2.5 µg per 100 gm body weight daily for 7 months, beginning 10 days before methylcholanthrene treatment was started, only slightly altered the carcinogenic response of rats to methylcholanthrene. Chronic administration of propylthiouracil during the same period significantly inhibited mammary cancer induction by methylcholanthrene. However, in rats initially made hypothyroid by propylthiouracil administration, but in which the thyroidal status was subsequently reversed by administration of thyroxin (2.5 µg per 100 gm body weight daily) beginning 10 days after cessation of carcinogen feedings, the incidence and latency of appearance of mammary cancer were not different from control rats treated with methylcholanthrene only. These data suggest that modifications of the carcinogenic response of rats to methylcholanthrene as a result of altered thyroid hormone levels were due principally to the growth-promoting stimulus of thyroid hormone, or lack of it, upon established neoplastic cells.

Prenatal treatment of fetal hypothyroidism: is there more than one option?

Abstract: Following the diagnosis of fetal goitre at 22 and 24 weeks' gestation in two hyperthyroid pregnant women who underwent treatment with 400-500 mg of propylthiouracil in the first weeks of pregnancy, a total of seven fetal blood samplings were performed to evaluate thyroid function before and after the initiation of two different treatment regimens. L-Thyroxine (600 micrograms) was injected five times intra-amniotically in one woman and continuous maternal administration of the thyroid analogue 3, 5, 3'-triiodothyroacetic acid (Triac) was attempted in the other. Normalization of fetal thyroid function and reduction of fetal goitre were achieved in both fetuses and transplacental passage of Triac was indirectly demonstrated by high levels of free triiodothyronine in fetal blood. In cases of fetal hypothyroidism, direct or indirect prenatal therapy can be adopted successfully and safely.

TSH-Induced Appearance and Stimulation of Amine-Containing Mast Cells in the Mouse Thyroid

Abstract: Intra- and extrathyroidal mast cells in mice were located by their metachromasia and histochemically demonstrable 5-hydroxytryptamine (5-HT) and histamine content, and plasma TSH levels were determined by bioassay. Untreated mice had no detectable plasma TSH ( <0.1 mU/ml), and no or very few intrathyroidal mast cells, whereas numerous mast cells were found in adjacent tissues. During propylthiouracil (PTU) treatment, plasma TSH rose progressively (to 4.0 mU/ml at 4 weeks) and several amine-containing mast cells appeared in the thyroid. Concomitant administration of thyroid hormone prevented these effects, and withdrawal of PTU was followed by decreased plasma TSH levels and a disappearance of the thyroid mast cells. However, the content of amines and metachromatic material in thyroid mast cells seemed inversely related to the plasma TSH level. The extrathyroidal mast cells were never affected by changes in TSH. The findings indicate that, in mice, TSH induces the appearance of 5-HT-and histamine-containin...