Glucocorticoid receptor expression in nontumorous human pituitaries and pituitary adenomas

Glucocorticoids have multiple actions, including a suppressive feedback eff ect on pituitary corticotrophs via the glucocorticoid receptor (GR). By imm unocytochemistry, we studied GR expression in 86 surgically removed various pituitary adenoma types. Ten cases contained nontumorous pituitary fragmen ts, which were suitable for immunocytochemical investigation. In addition, 30 autopsy-obtained pituitaries, 10 of them containing incidental microaden omas, were examined as well. Using a polyclonal GR antibody, the streptavid in-biotin-peroxidase complex method revealed nuclear and/or cytoplasmic GR immunoreactivity in many nontumorous corticotrophs and other adenohypophysi al cell types and in S-100 protein immunopositive stellate cells. Cellular localization was confirmed by double immunostaining. Pars intermedia cortic otrophs, posterior lobe axons, Herring bodies, and pituicytes as well as se veral endothelial cells lining the capillaries were also immunopositive. CR immunoreactivity was also demonstrated in many GH, PRL, ACTH, TSH, FSH, LH a-subunit producing adenomas, null cell adenomas, and oncocytomas. The ext ent and degree of immunostaining varied considerably from case to case. Sup pressed corticotrophs showing the Crooke's hyaline change due to glucocorti coid excess were present in the nontumorous pituitaries of patients with Gu shing's disease and in those treated with pharmacologic doses of glucocorti coids. Many suppressed nontumorous corticotrophs exhibited only weak or no CR immunopositivity, indicating GR downregulation accompanied by cellular i njury. Study of autopsy obtained pituitaries for GR yielded inconclusive re sults indicating that autopsy obtained adenohypophyses are not suitable for the immunocytochemical investigation of GR.