Iodothyronine 5-deiodinase in rat posterior pituitary.
We first describe the presence of iodothyronine 5-deiodinase (5D) in the neural lobe of rat pituitary. 6-n-Propyl-2-thiouracil (PTU), a specific inhibitor of type-I deiodinase, had no effect, showing that 5D in neurohypophysis is of type-III isozyme, which is specific for 5-deiodination and has been found only in the brain, placenta and skin. The presence of 5D (type-III) together with our previous report of 5'-deiodinase (type-I in euthyroidism and type-II in hypothyroidism) shows that the isozymes of deiodinases in the neurohypophysis are quite similar to those in the brain. These data suggest a previously unrecognized role of thyroid hormone in posterior pituitary physiology.
Tanaka
K
K
Department of Internal Medicine, Kyoto University, Faculty of Medicine, Japan.
Shimatsu
A
A
Imura
H
H
D000818:Animals; D002851:Chromatography, High Pressure Liquid; D004229:Dithiothreitol / Q000494:pharmacology; D007453:Iodide Peroxidase / Q000378:metabolism*; D007527:Isoenzymes / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D010903:Pituitary Gland, Anterior / Q000201:enzymology; D010904:Pituitary Gland, Posterior / Q000201:enzymology*; D011441:Propylthiouracil / Q000494:pharmacology; D051381:Rats; D017208:Rats, Wistar; D013963:Thyroid Hormones / Q000302:isolation & purification / Q000378:metabolism; D001615:beta-Endorphin / Q000032:analysis
D007527:Isoenzymes; D013963:Thyroid Hormones; D001615:beta-Endorphin; D011441:Propylthiouracil; D007453:Iodide Peroxidase; D004229:Dithiothreitol