title: [Modulation of T4 to T3 conversion. Comparative aspects (author's transl)].
abstract: The peripheral conversion of T4 to T3 has been demonstrated in primitive Vertebrates, larval Lampreys (which do not have thyroid follicles but synthesize T3 and T4 in the endostyle) and in more evolved Vertebrates. Up to now the presence of rT3 has never been demonstrated in fish, its eventual role in Amphibia remains to be established but seems important in chick embryo. The conversion of T4 to T3 is stimulated during amphibian metamorphosis and in salt water fish, concurrently with stimulation of thyroidal secretion. In fish, prolactin stimulates 5-deiodination of T4 directly without the involvement of the pituitary thyroid axis.
mesh_terms: D000663:Amphibians / Q000378:metabolism; D000818:Animals; D001717:Birds / Q000378:metabolism; D002642:Chick Embryo; D005399:Fishes / Q000378:metabolism; D007798:Lampreys / Q000378:metabolism; D008322:Mammals / Q000378:metabolism; D011388:Prolactin / Q000494:pharmacology; D013045:Species Specificity; D013974:Thyroxine / Q000378:metabolism*; D014284:Triiodothyronine / Q000096:biosynthesis*; D014714:Vertebrates / Q000378:metabolism*
chemical_list: D014284:Triiodothyronine; D011388:Prolactin; D013974:Thyroxine
vernacular_title: Modulation de la conversion de T4 en T3. Aspects comparatifs.