Correlative studies between the presence of thyrotropin-releasing hormone (TRH) receptors and the in vitro stimulation of growth-hormone (GH) secretion in human GH-secreting adenomas.
Specific receptors for TRH were characterized on cellular membranes of 6 out of 13 somatotrophic adenomas obtained from acromegalic patients. These receptors had the same dissociation constant (Kd: 62 +/- 10 nM) as those found in human PRL-secreting adenomas, but their maximal number of binding sites (Bmax: 76 +/- 24 fmol/mg of protein) was six fold smaller. A good correlation was found between the presence of TRH receptors and the in vitro TRH-induced stimulation of GH secretion. The increase in GH release varied from 25 to 200%. It was thus concluded that these receptors are functional. However, why only some of the human somatotrophic adenomas possess TRH receptors and respond to TRH in vitro needs further investigations.
Le Dafniet
M
M
Garnier
P
P
Bression
D
D
Brandi
A M
AM
Racadot
J
J
Peillon
F
F
D000236:Adenoma / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D007987:Gonadotropin-Releasing Hormone / Q000378:metabolism; D013006:Growth Hormone / Q000378:metabolism*; D006801:Humans; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D018025:Receptors, Thyrotropin-Releasing Hormone; D013004:Somatostatin / Q000378:metabolism; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*; D005680:gamma-Aminobutyric Acid / Q000378:metabolism
D011956:Receptors, Cell Surface; D018025:Receptors, Thyrotropin-Releasing Hormone; D007987:Gonadotropin-Releasing Hormone; D013004:Somatostatin; D005680:gamma-Aminobutyric Acid; D013973:Thyrotropin-Releasing Hormone; D013006:Growth Hormone