Human plasma growth hormone (GH)-binding proteins are regulated by GH and testosterone.
Possible regulation of GH-binding proteins (GH-BPs) in human plasma was examined. Eight children with isolated GH deficiency had a very low level of plasma GH-binding activity (10.2 +/- 1.1% of radioactivity). Under GH treatment the hormone binding to the high affinity BP (peak II-BP) increased in every patient to reach the mean value of 18.5 +/- 1.4%. In one patient, Scatchard plot analysis indicated that this increase was related to a higher binding capacity without any significant change in the binding affinity. A positive correlation existed between the GH-binding activity and insulin-like growth factor-I plasma levels. In nine boys with pubertal delay, the GH-specific binding to peak II-BP was normal (30.6 +/- 3.7% of radioactivity); it decreased significantly after testosterone treatment. In four boys with precocious puberty, the specific GH binding to peak II-BP was low (16.6 +/- 1.1%). It increased significantly to 21.6 +/- 1.1% of radioactivity after treatment with a LHRH analog. A negative correlation existed between plasma testosterone levels and GH binding to peak II-BP in boys presenting pubertal delay or precocious puberty. The high affinity GH-BP is regulated, and among the factors that play a role in this regulation, GH and testosterone have opposite effects.
Postel-Vinay
M C
MC
Unité de Biologie et Pathologie de la Croissance et du Développement, INSERM Unité 30, Hôpital des Enfants-Malades, Paris, France.
Tar
A
A
Hocquette
J F
JF
Clot
J P
JP
Fontoura
M
M
Brauner
R
R
Rappaport
R
R
D000293:Adolescent; D002352:Carrier Proteins / Q000097:blood*; D002648:Child; D002675:Child, Preschool; D013006:Growth Hormone / Q000097:blood / Q000172:deficiency / Q000502:physiology*; D006801:Humans; D007334:Insulin-Like Growth Factor I / Q000378:metabolism; D008297:Male; D011628:Puberty, Delayed / Q000097:blood / Q000188:drug therapy; D011629:Puberty, Precocious / Q000097:blood; D013739:Testosterone / Q000097:blood / Q000502:physiology* / Q000627:therapeutic use
D002352:Carrier Proteins; D013739:Testosterone; D007334:Insulin-Like Growth Factor I; D013006:Growth Hormone; C051815:somatotropin-binding protein