Effects of ACTH on adrenal angiotensin II receptor subtype expression in vivo

Control of adrenal aldosterone secretion is an important endocrine mechanis m mediated by angiotensin II (Ang. II). Recently three subtypes of angioten sin receptors have been demonstrated in the rat adrenal. Our aim was to exa mine if these receptors are affected by hormone treatment in vivo. Treatmen t of rats with ACTH resulted in a decrease in AT2 receptor binding from 766 +/- 95 to 310 +/- 51 fmol/mg protein (P < 0.05), without significant chang es in AT1 receptors. AT2 receptor mRNA was also decreased (18 +/- 2% of con trol, P < 0.05; 25 +/- 7% of control, P < 0.05) after both 2 and 7 day trea tment with ACTH. Changes in AT1a receptor mRNA or total AT1 mRNA did not re ach statistical significance. Moreover, treatment with dexamethasone or ald osterone did not affect AT1a, AT1b, or AT2 mRNA. These results demonstrate that ACTH treatment results in subtype-specific changes in adrenal AT recep tor gene expression in vivo. (C) 1998 Elsevier Science Ireland Ltd. All rig hts reserved.