Effects of growth hormone-releasing hormone (GHRH) on densely granulated somatotroph adenomas and sparsely granulated somatotroph adenomas in vitro: a morphological and functional investigation.

The effects of growth hormone-releasing hormone (GHRH) were studied on densely granulated somatotroph adenoma cells and sparsely granulated somatotroph adenoma cells in culture by measuring release of growth hormone (GH) as well as ultrastructural morphometrical parameters and comparing them with those of control adenoma cells. Both types of adenoma cells cultured with GHRH showed similar increases of GH release into culture media and exhibited similar increases in cytoplasmic volume densities (CVD) of endoplasmic reticulum and Golgi apparatus and decreases in CVD of secretory granules and secretory granule diameter. These results indicate that (1) both types of somatotroph adenoma cells react similarly to GHRH stimulation, despite their morphologic differences, and (2) GHRH stimulates GH synthesis as well as GH release by somatotroph adenoma cells.