AJP - Endocrinology and Metabolism, Vol 265, Issue 3 E521-E524, Copyright © 1993 by American Physiological Society
5'- and 5-deiodinase activities in adult rat cecum and large bowel contents inhibited by intestinal microflora
T. T. Nguyen, J. J. DiStefano 3rd, L. M. Huang, H. Yamada and H. J. Cahnmann
Biocybernetics Laboratory, University of California, Los Angeles 90024-1596.
Enzymatic mechanisms for deiodination of 3,5,3'-triiodothyronine or
thyroxine in the phenolic ring (5'-deiodinase) or tyrosyl ring
(5-deiodinase) are found in cells of many organs, including the intestinal
wall. Deiodinases are highly active in intestinal tissue of developing rat
fetuses and relatively inactive in adult intestinal cells, but little is
known about these systems in the luminal contents of intestines. We have
found both 5- and 5'-deiodinase activities in adult rat intestinal contents
and have shown that their expression is inhibited by resident intestinal
microflora, which are normally present in the adult but not in the fetus,
possibly because they are bound by intestinal bacteria in the adult.
