Somatostatin receptors in human growth hormone and prolactin-secreting pituitary adenomas.
[125I-Tyr]Somatostatin [( 125I-Tyr]SRIH) binding was found in 11 GH-secreting pituitary adenomas [Kd = 0.46 +/- 0.15 (+/- SE) nM; maximum binding, 165 +/- 35 fmol/mg protein). This binding was specific, since it was displaced by somatostatin-14 (SRIH-14), N-Tyr-SRIH-14, and SRIH-28. In contrast, a number of peptides and drugs not structurally related to SRIH, such as bombesin, dopamine, LHRH, met-enkephalin, naloxone, neurotensin, secretin, substance P, TRH, or vasoactive intestinal peptide, did not affect [125I-Tyr]SRIH binding. [125I-Tyr]SRIH specific binding also was found in PRL-secreting pituitary adenomas. The kinetic characteristics of the specific binding were similar to those of GH-secreting adenomas. However, maximal binding was one quarter that of GH-secreting adenomas (37 +/- 9 fmol/mg protein). In contrast, nonsecreting (chromophobe) tumors were devoid of any specific binding. Finally, in acromegaly, the density of [125I-Tyr]SRIH-binding sites in the adenomas was negatively correlated with plasma GH levels before surgery (r = -0.80). This suggests that somatostatinergic control is involved in GH secretion in acromegalic patients.
Moyse
E
E
Le Dafniet
M
M
Epelbaum
J
J
Pagesy
P
P
Peillon
F
F
Kordon
C
C
Enjalbert
A
A
D000172:Acromegaly / Q000378:metabolism; D000236:Adenoma / Q000378:metabolism*; D005260:Female; D013006:Growth Hormone / Q000097:blood / Q000378:metabolism*; D006801:Humans; D008297:Male; D010911:Pituitary Neoplasms / Q000378:metabolism*; D011388:Prolactin / Q000378:metabolism*; D011956:Receptors, Cell Surface / Q000378:metabolism*; D017481:Receptors, Somatostatin; D013004:Somatostatin / Q000031:analogs & derivatives / Q000378:metabolism; D053561:Somatostatin-28
D011956:Receptors, Cell Surface; D017481:Receptors, Somatostatin; C017426:somatostatin, iodine-Tyr-; D013004:Somatostatin; D053561:Somatostatin-28; D011388:Prolactin; D013006:Growth Hormone