Ontogeny of type I and type III deiodinase activities in embryonic and posthatch chicks: relationship with changes in plasma triiodothyronine and growth hormone levels.
1. The ontogeny of type I and type III deiodinase activities was studied in embryonic and posthatch chicks. 2. Hepatic type I activity showed a 3-fold increase up to the period of pipping and hatching and decreased slowly thereafter. 3. Hepatic type III activity increased by 3-fold from E14 to E17 and decreased more than 10-fold from E17 to C0. Posthatch levels were very low. 4. Type I activity in the kidney decreased slowly after hatching while type III activity was very low over the whole period studied. 5. Developmental changes during the late embryonic period suggest a causal relationship between the increase in plasma GH and T3 levels and the decrease in hepatic type III activity.
Laboratory of Comparative Endocrinology, K.U. Leuven, Belgium.
V M
VM
Darras
T J
TJ
Visser
L R
LR
Berghman
E R
ER
Kühn
D000818:Animals; D002642:Chick Embryo / Q000201:enzymology / Q000254:growth & development*; D002645:Chickens / Q000097:blood / Q000254:growth & development*; D013006:Growth Hormone / Q000097:blood*; D007453:Iodide Peroxidase / Q000378:metabolism*; D007668:Kidney / Q000201:enzymology; D008861:Microsomes / Q000201:enzymology; D008862:Microsomes, Liver / Q000201:enzymology; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood*
D014284:Triiodothyronine; D013006:Growth Hormone; D007453:Iodide Peroxidase; D013974:Thyroxine