1. The influence of methimazole on the thyrotrophic and peripheral activity of thyrotrophin and thyrotrophin-releasing hormone in the chick embryo and growing chicken.
- Author
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Iqbal A, Decuypere E, Kuhn ER, Schneider R, Verheyen G, and Huybrechts LM
- Subjects
- Animals, Female, Injections, Intravenous, Iodide Peroxidase metabolism, Male, Thyroid Gland enzymology, Thyrotropin administration & dosage, Thyrotropin-Releasing Hormone administration & dosage, Chick Embryo drug effects, Chickens physiology, Methimazole pharmacology, Thyroid Gland drug effects, Thyrotropin pharmacology, Thyrotropin-Releasing Hormone pharmacology, Thyroxine blood, Triiodothyronine blood
- Abstract
Plasma concentrations of thyroxine (T4) and triiodothyronine (T3) were profoundly depressed both in chick embryos and growing chickens after methimazole (MMI) treatment. There was no response of T4 and T3 levels to TRH or TSH injections in the MMI group, either in embryos or growing chickens. Peroxidase activity measured in the thyroid gland was significantly higher in embryos and growing chickens treated with MMI. However, neither TRH nor TSH affected this activity 2 hr after injection in either control or the MMI-treated group. Hepatic 5'-monodeiodinase activity was significantly stimulated in the MMI-treated groups of embryos and growing chickens but only when additional sulphydryl groups (DTT) were provided. In embryos, monodeiodination activity 2 hr after TSH injection was not significantly different from control values for either DTT-stimulated or unstimulated conditions within the control and MMI-infused groups. However, in both control and MMI-treated embryos monodeiodination activity significantly increased 2 hr after TRH injection. In the growing chickens, monodeiodination activity 2 hr after TRH or TSH injection was not significantly different from control values in either stimulated or unstimulated conditions of each group.
- Published
- 1987
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