Growth hormone axis in cushing's syndrome.
All levels of the growth hormone (GH), GH binding protein (GHBP), insulin-like growth factor (IGF) and IGF binding protein (IGFBP) axis are influenced by chronic hypercortisolism. Thus, there is a blunted response to GHRH alone or together with other stimuli associated with a marked suppression of endogenous GH secretion but accompanied by normal GHBP, normal to low IGF-1 and GHBPs 1 and 3 with the correspondent 41.5 and 38.5-kD molecular forms of the latter presenting values similar to normal. These findings may suggest enhanced GH sensitivity with normal or increased IGF-1 bioavailability to the correspondent tissue receptors. In conclusion, the glucocorticoid (GC)-induced target tissue resistance can neither be attributed to the suppression of the GH axis nor to changes in circulating GHBPs 1 and 3. However, it may be related either to the described 12-to-20-kD inhibitor(s) which antagonizes postbinding IGF-1 bioactivity (gene expression) and/or by the downmodulation of activator protein-1 (Fos/Jun) activity by the GC-GC receptor complex.
Wajchenberg
B L
BL
Endocrine Service, University of São Paulo Medical School, Brazil.
Liberman
B
B
Giannella Neto
D
D
Morozimato
M Y
MY
Semer
M
M
Bracco
L O
LO
Salgado
L R
LR
Knoepfelmacher
M
M
Borges
M H
MH
Pinto
A C
AC
Kater
C E
CE
Lengyel
A M
AM
D002352:Carrier Proteins / Q000502:physiology*; D003480:Cushing Syndrome / Q000503:physiopathology*; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism / Q000502:physiology*; D013007:Growth Hormone-Releasing Hormone; D006801:Humans; D018969:Insulin-Like Growth Factor Binding Proteins / Q000502:physiology*; D007334:Insulin-Like Growth Factor I / Q000502:physiology*; D008297:Male; D008954:Models, Biological; D012016:Reference Values
D002352:Carrier Proteins; D018969:Insulin-Like Growth Factor Binding Proteins; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; D013007:Growth Hormone-Releasing Hormone; C051815:somatotropin-binding protein