GLYCOPROTEIN HORMONE ALPHA‐SUBUNIT AND PROLACTIN RELEASE BY CULTURED PITUITARY ADENOMA CELLS FROM ACROMEGALIC PATIENTS: CORRELATION WITH GH RELEASE

In‐vitro data of pituitary adenoma cells from 28 acromegalic patients were evaluated. In addition to GH, PRL was produced by 16 adenomas (57%) and alpha‐subunit by 15 adenomas (54%) while there was a significantly higher incidence of tumours producing PRL and alpha‐subunit simultaneously. From 26 pituitary adenomas enough cells were obtained in order to perform secretion studies. Percentage basal hormone release (medium: (medium + intra‐cellular hormone)) ± 100% of GH and alpha‐subunit by 11 adenomas showed a close correlation while such a correlation for GH and PRL was present only in a subgroup of 10 of 13 adenomas. The responses of GH and alpha‐subunit release to 10nM SMS201–995, 10nM bromocriptine, 100nM TRH and 10nM GHRH were closely related in that a response or an absent response of GH release to the four secretagogues was virtually always attended with a response or an absent response respectively of alpha‐subunit release. Such a relationship was less evident with respect to the effects of SMS201–995, bromocriptine, TRH and GHRH on GH and PRL release. We conclude that basal and secretagogue‐induced alpha‐subunit release by cultured pituitary adenoma cells from acromegalic patients closely follows the pattern of GH release while such a relationship for GH and PRL is present only in a subgroup of the adenomas secreting GH and PRL simultaneously.