5-Hydroxytryptamine 2A receptor signaling cascade modulates adiponectin and plasminogen activator inhibitor 1 expression in adipose tissue

Knowledge of the regulatory factors associated with down-regulation of adiponectin gene expression and up-regulation of PAI-1 gene expression is crucial to understand the pathophysiological basis of obesity and metabolic diseases, and could establish new treatment strategies for these conditions. We showed that expression of 5-HT2A receptors was up-regulated in hypertrophic 3T3-L1 adipocytes, which exhibited decreased expression of adiponectin and increased expression of PAI-1. 5-HT2A receptor antagonists and suppression of 5-HT2A receptor gene expression enhanced adiponectin expression. Activation of Gq negatively regulated adiponectin expression, and inhibition of mitogen-activated protein kinase reversed the Gq-induced effect. Moreover, the 5-HT2A receptor blockade reduced PAI-1 expression. These findings indicate that antagonism of 5-HT2A receptors in adipocytes could improve the obesity-linked decreases in adiponectin expression and increases in PAI-1 expression. (C) 2008 Federation of European Biochemical Societies. Published by Elsevier B. V. All rights reserved.