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Human TRH receptor messenger ribonucleic acid levels in normal and adenomatous pituitary: analysis by the competitive reverse transcription polymerase chain reaction method
Author(s) -
Kaji Hidesuke,
Xu Yue,
Takahashi Yutaka,
Abe Hiromi,
Tamaki Norihiko,
Chihara Kazuo
Publication year - 1995
Publication title -
clinical endocrinology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.055
H-Index - 147
eISSN - 1365-2265
pISSN - 0300-0664
DOI - 10.1111/j.1365-2265.1995.tb01871.x
Subject(s) - pituitary disease , biology , complementary dna , adenoma , endocrinology , medicine , pituitary gland , prolactinoma , pituitary tumors , anterior pituitary , receptor , messenger rna , pituitary adenoma , reverse transcription polymerase chain reaction , acromegaly , microbiology and biotechnology , gene , hormone , prolactin , genetics , growth hormone
Summary OBJECTIVE Little is known about the mechanism of diversity in in‐vivo hormonal responsiveness to TRH in patients with functional pituitary adenomas. In order to clarify the relation between the responsiveness to TRH and TRH receptor messenger ribonucleic acid (mRNA) expression, we attempted to measure TRH receptor mRNA levels in human pituitary adenoma tissues by competitive reverse transcription polymerase chain reaction (RT‐PCR) method. PATIENTS Pituitary tissue samples were obtained at autopsy from 5 patients without pituitary disease. Pituitary adenoma tissue samples were obtained at surgery from 18 patients with pituitary adenoma (4 non‐functioning, 8 pro‐lactinoma, 4 acromegaly, 1 Cushing's disease and 1 FSH producing adenoma). METHODS Partial TRH receptor cDNA from a human GH producing adenoma cDNA library was ampilfied by PCR under low stringency conditions using primers encoding the transmembrane domains III and VI of pituitary TRH receptor cDNA. The partial sequence of the amplified cDNA determined by a dideoxy‐chain termination method was identical to the corresponding sequence of human TRH receptor cDNA. A competitor was generated by deleting the inner 111 bp from the amplified TRH receptor cDNA and subcloning. RNA extracted from human pituitary was reverse transcribed and co‐amplified with competitor by PCR under higher stringency conditions. The TRH receptor mRNA levels, expressed as the relative intensity against the amplified levels of competitor, were compared among various pituitary tissues. RESULTS The relative TRH receptor mRNA levels of pituitary tissues in patients without pituitary disease were detectable and variable (M±SD) (0·370 ± 0·231, n = 5), and slightly but not significantly lower than those in patients with pituitary tumours (0·598 ± 0·265, n = 18). In patients with prolactinoma, the relative levels of TRH receptor mRNA were quite variable (0·02–1·170, 0·604 ± 0·358, n = 8) and not correlated with PRL responsiveness to TRH (responder 0·457; non‐responder 0·340–0·950). In patients with acromegaly, TRH receptor mRNA was detectable not only in the paradoxical GH responder to TRH (0·718) but also In the non‐responder (0·758 and 0·765). In one patient with Cushing's disease, a relatively low level of TRH receptor mRNA could be detected (0·415). In the patient with a FSH producing tumour whose plasma FSH did not respond to TRH, a small amount of TRH receptor mRNA was detectable (0·447). CONCLUSIONS in patients with functioning pituitary adenomas, hormonal responsiveness to TRH in vivo might not be assessable by TRH receptor mRNA levels in the adenoma cells.