In-vitro effects of bromocriptine on isolated pituitary adenoma cells. Ultrastructural and morphometrical studies.

3 pituitary adenomas in hyperprolactinemia and 3 GH and prolactin producing tumours were analysed. The adenoma cells were prepared and held in suspension so that they could be treated with bromocriptine (10 ng and 100 ng). At different times after treatment (0.5, 60 and 90 minutes), the cells were fixed and prepared for conventional electronmicroscopy. Electron microscopic photographs were quantitatively analysed by the point counting method. The results were compared to those of an untreated control group. After bromocriptine influence, there was a decrease of the hormone secretion into the supernatant (2 of 3 prolactin producing adenomas). The prolactin secretion was unchanged in all 3 adenomas which produced prolactin and GH, but there was a decrease in the GH production in 1 of these cases. Ultrastructural morphometry revealed the following results: In prolactin producing adenomas, there was a decrease in the number of exocytoses, an increase in the volume density of lysosomes (2 cases) and an increase of the rough endoplasmic reticulum (1 case). The decrease of the "unorganized" cytoplasm was observed in all 3 cases, but was significant only in 1 case. There was a significant increase in secretory granules (1 case). In adenomas which produced prolactin and GH displayed a significant increase of the rough endoplasmic reticulum and of the granules. The outlines of the cellular membranes seemed smoother (1 case). The heterogeneous results may be interpreted as an expression of the reduced hormone secretion (secretory granules, lysosomes), some data are in accordance with the beginning of necrobiotic phenomena (rough endoplasmic reticulum). The decrease of the "unorganized" cytoplasm may be due to a shrinking process.