Preoperative normalization of cortisol levels in cushing's disease after medical treatment: Consequences for somatostatin and dopamine receptor subtype expression and in vitro response to somatostatin analogs and dopamine agonists

Context: Corticotroph pituitary adenomas often highly express the dopamine 2 receptor (D2R) and somatostatin receptor subtype 5 (sst5). The sst2 expression is relatively low, likely resulting from downregulating effects of high cortisol levels. This may explain why the sst2-preferring somatostatin analog octreotide, compared with the multi-receptor-targeting somatostatin analog pasireotide, is generally ineffective in Cushing's disease. Objective: Our objective was to compare sst and D2R expression levels between adenomas from patients with elevated and normalized preoperative urinary free cortisol excretion. Patients and Design: Corticotroph adenoma tissue was examined from patients from group 1 (n = 22; elevated preoperative urinary free cortisol) and group 2 (n = 11;meanduration of preoperative normocortisolism 10 weeks). Somatotroph adenoma tissue from 10 acromegalic patients was examined to compare receptor expression profiles. Main Outcome Measures: We evaluated receptor mRNA and protein expression levels and effects of octreotide,pa