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Extrathyroidal conversion of thyroxine to 3,5,3'-Triiodothyronine (T3) and 3,5',3'-triiodothyronine (T3) and its contribution to total triiodothyronines production rates in fed and food restricted piglets



Extrathyroidal conversion of thyroxine to 3,5,3'-Triiodothyronine (T3) and 3,5',3'-triiodothyronine (T3) and its contribution to total triiodothyronines production rates in fed and food restricted piglets



Journal of Veterinary Medicine, A Animal Physiology, Pathology and Clinical Veterinary Medicine 33(5): 337-348



Studies of extrathyroidal conversion of thyroxine on T3 and rT3 and the contribution of peripheral thyroxine (T4) monodeiodination to the production of T3 and rT3 were carried out in 6-8 weeks old fed and starved piglets. Thyroidal secretion added 30% of T3 and 7.2% of rT3 to total daily production of the triiodothyronines. 70% of T3 and 92.8% of rT3 were derived from peripheral monodeiodination of T4. Food restriction caused a fall in serum T4, FT4 and T3 concentrations, a rise in serum rT3 concentration and a marked reduction of MCRs and production rates of T4 and both triiodothyronines. In fasted animals thyroidal secretion added only 17% of T3 and 2.9% of rT3 to their total production. 83% of T3 and 97.1% of rT3 were generated from the peripheral conversion of T4. The reduced T3 secretion and generation on the periphery, leading to a fall in the metabolically active thyroid hormone, may represent an adaptive mechanism protecting the organism from loss of energy and protein reserves during starvation.

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Accession: 001364995

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PMID: 3094291



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Extrathyroidal conversion of thyroxine to 3 5 3 triiodothyronine and 3 3' 5' triiodothyronine and its contribution to total triiodothyronines production rates in fed and food restricted piglets. Journal of Veterinary Medicine Series A 33(5): 337-348, 1986

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