Bromocriptine-Induced Changes in Hormone Secretion and Cell Morphology in Growth Hormone and Prolactin Producing Pituitary Adenomas

Abstract

Of 2 patients with GH-producing adenomas and 2 patients with prolactinomas treated with bromocriptine prior to operation. morphological changes in B limited number of pituitary tumour cells were observed only in 2 cases of PRL-secreting adenomas. The 2 patients with hypersecretion of GH did not show morphological damage of the pituitary tumour cells. [In vitro incubation of post-pregnancy hyperplastic pituitary tissue with 0.1 and (1.001 μ/Uml of bromocriptine did not affect hormone secretion or cell morphology. Tissue cultured in vitro from the prolactinomas exposed to bromocriptine in vivo prior to operation was affected with regard to both hormone recretion and cell morphology when expming organ cultures to 0.l and 0.01 μg/ml of bromocriptine. However. considerable variations in morphological damage occurred between the various parts of the tumour. GH secretion in prolactinomas was not affected by bromocriptine. In organ cultures of tumours with concomitant over-secretion of GH and PRL. an inhibition of the synthesis/ secretion of PRL occurred without morphological evidence of cell damage when using concentrations of 0.l and 0.01 μg/ml of bromocriptine. Ultrastructurally an increahed number of lysosomes was indicated in exposed organ cultures. In tumours primarily secreting GH. incubation of organ cultures with bromocriptine caused individual variations of hormone secretion among the tumom. In one. the concentration of 0.1–1.0 μg/ml of bromocriptine caused a decrease of the PRL levels in the culture media. whereas in other tumours these concentralions did not affect PRL levels. The secretion of GH into the culture medium was not affected by hromocriptine in concentrations 0.001–1.0 μg/ml during incubation for 420 days. Pituitary tumour cells in vivo expoyed to bromocriptine frequently showed extensively pleomorphic secretory granules. This ultrastructural abnormality disappeared when culturing specimens in the in vitro system.