Altered responsiveness to hypophysiotrophic hormones of perifused rat pituitary tumours.
PMID 190840 · Acta endocrinologica · 1977 · DOI 10.1530/acta.0.0840512
Authors: H E Carlson; I K Mariz; J E Briggs; W H Daughaday
Abstract
Since growth hormone (GH) and prolactin (Prl) secretion by human pituitary tumours is often influenced by the hypophysiotrophic hormones thyrotrophin-releasing hormone (TRH) and somatostatin (SRIF), we have examined the responses of several transplantable rat pituitary tumours to these substances in a perifusion apparatus. The MStT/W15 tumour did not alter its secretion of GH and Prl in response to TRH, SRIF, or a partially purified porcine hypothalamic extract containing GH-releasing activity; normal rat pituitaries show clear responses to each of these substances. Theophylline and dibutyryl cyclic AMP each provoked increased GH and Prl release from the tumour. A second specimen of the MStT/W15 tumour and a specimen of the MStT/W5 tumour behaved in a manner identical to the original MStT/W15, showing no response to TRH or SRIF, but releasing both GH and Prl when theophylline or dibutyryl cyclic AMP was given. The MtT/F4 tumour increased its secretion of GH in response to TRH, 10 mug/ml, and theophylline, but no effect was seen with lower concentrations of TRH or with SRIF; Prl secretion by the F4 tumour was increased by theophylline, but TRH and SRIF had no effect. The autonomy demonstrated in these experimental tumours may be due to a loss of specific hypophysiotrophic hormone receptors or of secretory activating mechanisms.
Animals; Bucladesine; Drug Synergism; Female; Growth Hormone; Hypothalamus; Neoplasms, Experimental; Perfusion; Pituitary Gland, Anterior; Pituitary Neoplasms; Prolactin; Rats; Receptors, Cell Surface; Somatostatin; Theophylline; Thyrotropin-Releasing Hormone
Cite
H E Carlson; I K Mariz; J E Briggs; W H Daughaday. Altered responsiveness to hypophysiotrophic hormones of perifused rat pituitary tumours. Acta endocrinologica (1977). PMID 190840. DOI 10.1530/acta.0.0840512.