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Cell. 2009 Dec 24;139(7):1353-65. doi: 10.1016/j.cell.2009.11.034. Epub 2009 Dec 10.

Sensory neuron-specific GPCR Mrgprs are itch receptors mediating chloroquine-induced pruritus.

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  • 1The Solomon H. Snyder Department of Neuroscience, Center for Sensory Biology, School of Medicine, Johns Hopkins University, Baltimore, MD 21205, USA.


The cellular and molecular mechanisms mediating histamine-independent itch in primary sensory neurons are largely unknown. Itch induced by chloroquine (CQ) is a common side effect of this widely used antimalarial drug. Here, we show that Mrgprs, a family of G protein-coupled receptors expressed exclusively in peripheral sensory neurons, function as itch receptors. Mice lacking a cluster of Mrgpr genes display significant deficits in itch induced by CQ but not histamine. CQ directly excites sensory neurons in an Mrgpr-dependent manner. CQ specifically activates mouse MrgprA3 and human MrgprX1. Loss- and gain-of-function studies demonstrate that MrgprA3 is required for CQ responsiveness in mice. Furthermore, MrgprA3-expressing neurons respond to histamine and coexpress gastrin-releasing peptide, a peptide involved in itch sensation, and MrgprC11. Activation of these neurons with the MrgprC11-specific agonist BAM8-22 induces itch in wild-type but not mutant mice. Therefore, Mrgprs may provide molecular access to itch-selective neurons and constitute novel targets for itch therapeutics.

Copyright 2009 Elsevier Inc. All rights reserved.

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