Thyrotropin releasing hormone (TRH)-induced release of 7B2 (neuroendocrine polypeptide) in vivo and in vitro using adenoma cells of a patient with acromegaly

Abstract

We demonstrated TRH-induced release of 7B2 (a neuroendocrine polypeptide) in vivo and in vitro (somatotroph adenoma cells) in a patient with acromegaly. The mean basal plasma 7B2 and growth hormone (GH) levels before operation were 142.8 +/- 3.2 ng/l and 52.4 +/- 1.6 micrograms/l (mean +/- SEM), respectively and these levels significantly rose after an i.v. administration of 500 micrograms of thyrotropin releasing hormone (TRH). After the transsphenoidal adenomectomy, the basal level of plasma GH was restored to the normal level and that of plasma 7B2 was slightly decreased. In addition, TRH-induced response of plasma 7B2 and GH disappeared post-operatively. In a primary culture of somatotroph adenoma cells obtained at surgery, TRH significantly induced secretions of both 7B2 and GH. Immunohistochemical studies showed the positive 7B2 and GH immunoreactivities in somatotroph adenoma cells. These findings strongly suggest that the somatotroph adenoma cells in this case produced and released 7B2 concomitant with GH.