Adrenalectomy stimulates the formation of initial atherosclerotic lesions: reversal by adrenal transplantation

Abstract

Long-term changes in the secretion of immunosuppressive adrenal-derived glucocorticoid hormones influence cardiovascular disease risk. Here we determined the consequences of changes in adrenal steroid metabolism for the development of atherosclerotic lesions in mice. Atherosclerosis-susceptible low-density-lipoprotein (LDL) receptor knockout mice were subjected to adrenalectomy (ADX) or a control (SHAM) operation and subsequently fed an atherogenic diet for 4 weeks. Atherogenic diet feeding raised plasma corticosterone levels in SHAM mice, but not adrenalectomized mice, resulting in an 83% lower (P<0.01) corticosterone level in adrenalectomized mice. Adrenalectomy was associated with a respectively 22% and 29% lower plasma level of cholesterol and triglycerides. In contrast, white blood cell counts were increased 2-fold (P<0.01) in adrenalectomized mice, which could be attributed to a significant 2.1- to 2.6-fold rise in lymphocyte (P<0.05) and monocyte (P<0.05) numbers. Probably as a result of the enhanced systemic inflammatory status, adrenalectomy was associated with a higher susceptibility for diet-induced atherosclerosis (321±18×10(3) μm(2) for ADX vs 240±31×10(3) μm(2) for SHAM; P<0.05) not withstanding the lowered cholesterol levels. Restoring adrenocortical steroid secretion - but not adrenal medulla function - and the associated downstream glucocorticoid receptor signaling in adrenalectomized mice through adrenal transplantation induced a reversal of the adrenalectomy-associated rise in white blood cell numbers, plasma monocyte chemoattractant protein 1 (MCP-1) levels, and atherosclerotic lesion development (lesion size in transplanted mice: 258±34×10(3) μm(2); P<0.05 vs ADX). In conclusion, our studies show that adrenal-derived steroids protect against the development of initial atherosclerotic lesions in LDL receptor knockout mice.