In order to test for glucocorticoid regulation of CART in the arcuate nucleus, adrenalectomies (ADX) and hormone replacements (HRs) were carried out in groups of rats. CART mRNA levels were determined by in situ hybridization and CART peptide levels by immunocytochemistry. ADX caused a lowering of CART mRNA and peptides levels in the arcuate and this was reversed by HR. These results indicate a glucocorticoid regulation of CART in the arcuate. The regulation could be direct through an action of glucocorticoid receptors or indirectly through ADX-induced changes in leptin levels. These findings suggest a role for CART in the stress response. (C) 2003 Wiley-Liss, Inc.