Figure 2.

Catecholaminergic pathway in bilateral macronodular adrenal hyperplasia (BMAH) associated with Cushing’s syndrome. (A) Chromogranin A-positive chromaffin cells (arrows), which represent the main source of catecholamines in the normal adrenal gland, were in close contact with steroidogenic cells (arrow heads) in BMAH tissue. (B) Clonidine, an α2 receptor agonist, dose-dependently stimulated cortisol secretion by cultured adrenocortical cells derived from a BMAH tissue. Adapted from Ref. (47). (C) The maximum cortisol responses of cultured BMAH adrenocortical cells to high concentrations of ACTH (10⁻¹⁰ M) and clonidine (10⁻⁶ M) were not additive, suggesting that α2 and MC2R receptors are coupled to a common transduction pathway.