Evidence of thyrotropin-releasing hormone (TRH) and TRH-binding sites in human nonsecreting pituitary adenomas.
Immunoreactive TRH (IR-TRH) and TRH-binding sites were sought in nonsecreting pituitary adenomas. [3H]TRH bound specifically to cellular membranes from 11 of 12 such adenomas studied, with a dissociation constant (Kd) of 50 +/- 5 (+/- SEM) nmol/L and a maximum number of binding sites of 76 +/- 16 fmol/mg membrane protein (range, 32-229 fmol/mg protein). IR-TRH was detected in all 8 of the tumors in which it was sought. The identity of the IR-TRH was verified by high pressure liquid chromatography. The tumor IR-TRH concentration varied from 45-248 fmol/mg cell protein (mean, 109 +/- 28 fmol/mg cell protein), about half that in normal human pituitary (229 +/- 55 fmol/mg protein). There was no correlation between the number of binding sites and the IR-TRH content. The role of TRH in nonsecreting pituitary adenomas is unknown at this time.
D000236:Adenoma / Q000378:metabolism*; D000368:Aged; D001665:Binding Sites; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010902:Pituitary Gland / Q000378:metabolism; D010911:Pituitary Neoplasms / Q000378:metabolism*; D012016:Reference Values; D013973:Thyrotropin-Releasing Hormone / Q000378:metabolism*
D013973:Thyrotropin-Releasing Hormone