Human pituitary corticotroph adenomas in vitro: morphologic and functional responses to corticotropin-releasing hormone and cortisol.

We examined the direct effects of corticotropin-releasing hormone (CRH) and cortisol on the morphology of cells from 6 functioning human pituitary corticotroph adenomas in culture using both light and electron microscopic morphometry and correlated the structural changes with alterations in adrenocorticotropin (ACTH) release in each case. During incubations lasting 2 or 24 h, ACTH release was increased by CRH and reduced by cortisol. After incubations lasting from 2 to 72 h, light microscopic morphometric analysis showed no significant differences in cell size, nuclear area, cytoplasmic area or nuclear/cytoplasmic ratio between treated and control adenoma cells. Ultrastructural morphometry documented increased cytoplasmic volume density (CVD) of rough endoplasmic reticulum and/or Golgi apparatus and reduced CVD of secretory granules in cells incubated with CRH. There was no consistent change in CVD of endoplasmic reticulum, Golgi apparatus or secretory granules in adenoma cells incubated with cortisol, but in all tumors there were marked filament accumulations indicating a direct effect of cortisol on adenomatous corticotrophs. The changes were similar after 2- and 72-hour exposures. These results indicate that (1) some adenomatous corticotrophs can respond to CRH and cortisol; (2) the morphologic changes observed in cells treated with CRH correlate with increased ACTH release, and (3) accumulation of filaments is the direct effect of cortisol and is associated with reduced ACTH release.