Regulation of endorphin production by glucocorticoids in cultured pituitary tumor cells

When clonal AtT-20 mouse pituitary tumor cells were exposed in culture to physiological concentrations of glucocorticoids for 2 or more days, the intracellular endorphin content was reduced by 50–75%. The steroid specificity is consistent with a glucocorticoid-receptor mediated response. Gel filtration analysis indicates a reduction of both the major and the minor endorphin species present, which resemble β- and α-endorphin, respectively. The results suggest that endorphin synthesis, like corticotropin synthesis, is under negative regulatory control by glucocorticoids in AtT-20 cells and in the corticotropin/endorphin-producing cells of the adenohypophysis.