Bromocriptine-induced morphological changes in cultured growth hormone-producing pituitary adenoma cells

Tumor tissues obtained from two patients with growth hormone-producing pituitary adenomas were cultured and treated with bromocriptine, then examined for morphological changes. Untreated tumor cells (controls) were morphologically well preserved and in terms of growth hormone secretion. Tumor cells exposed to bromocriptine for 7 days contained many vacuoles, which, after 14 days of exposure, grew larger and more numerous. These vacuoles appeared to be extensions of endoplasmic reticulum: some were connected to rough or smooth endoplasmic reticulum or, occasionally, to Golgi apparatus, and there were ribosomes on their surfaces. Bromocriptine apparently has cytocidal effects on growth hormone-producing pituitary adenoma in vitro.