Thyrotropic activity of the ovine corticotropin-releasing factor in the chick embryo.
An injection of several doses of ovine corticotropin-releasing factor (oCRF) was made into an allantoic blood vessel of 18-day-old chick embryos. All doses used (0.5, 1, 2, and 5 micrograms) induce a quick increase of plasma corticosterone concentrations after 15 and 30 min and 1 and 2 hr and this in a dose-dependent manner with the high doses having a prolonged effect lasting up to 2 hr. An increase in plasma levels of thyroxine (T4) and triiodothyronine (T3) was observed after 1 and 2 hr. After the oCRF injection, no stimulation of the hepatic 5'-monodeiodination activity was observed and there was no increase, but even a small decrease in the T3 to T4 ratio could be calculated. It was therefore concluded that oCRF in the chick embryo has a thyrotropic effect presumably by stimulating the release of thyrotropin from the pituitary.
Meeuwis
R
R
Laboratory of Comparative Endocrinology, K.U.L., Belgium.
Michielsen
R
R
Decuypere
E
E
Kühn
E R
ER
D000324:Adrenocorticotropic Hormone / Q000378:metabolism*; D000818:Animals; D002642:Chick Embryo / Q000378:metabolism*; D003345:Corticosterone / Q000097:blood; D003346:Corticotropin-Releasing Hormone / Q000502:physiology*; D005938:Glucocorticoids / Q000097:blood*; D012756:Sheep; D013961:Thyroid Gland / Q000378:metabolism*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood
D005938:Glucocorticoids; D014284:Triiodothyronine; D000324:Adrenocorticotropic Hormone; D003346:Corticotropin-Releasing Hormone; D013974:Thyroxine; D003345:Corticosterone