Chronic stress is widely considered to trigger or enhance itch, especially for pruritic dermatitis. However, the molecular mechanisms linking chronic stress and itch are still unknown. The present study aimed to elucidate the role of adrenergic signaling in itch hypersensitivity following heterotypic chronic intermittent stress (HIS) in rats. HIS significantly increased hindlimb scratching, but not forepaw swiping, induced by intradermal injection of 5-hydroxytryptamine (5-HT) in the rat cheek. Coadministration of stress mediators such as norepinephrine or epinephrine dose-dependently increased both 5-HT-induced hindlimb scratching and 5-HT-induced forepaw swiping. HIS-induced itch hypersensitivity was attenuated by blockade of sympathetic signaling through guanethidine treatment, and systemic administration of the beta-adrenoceptor antagonist propranolol and the beta(2)-adrenoceptor antagonist butoxamine, but not on treatment with an alpha-adrenoceptor antagonist phentolamine and a beta(1)-adrenoceptor antagonist atenolol. Moreover, HIS selectively increased the expression of beta(2)-adrenoceptors and proinflammatory factors [tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta), and nerve growth factor (NGF)] in rat skin. The beta-blockers propranolol and butoxamine abolished the upregulation of proinflammatory factors. The beta(2)-adrenoceptor agonist terbutaline was sufficient to enhance the skin expression of TNF-alpha and IL-1 beta and to increase 5-HT-induced scratching in naive rats. Pretreatment with TNF-alpha could increase 5-HT-induced scratching. Together, these results demonstrate that beta(2)-adrenoceptors mediate itch hypersensitivity following chronic stress by inducing proinflammatory factors, such as TNF-alpha, in the skin. Copyright (C) 2015 Wolters Kluwer Health, Inc. All rights reserved.