Selective Inhibition of Thermosensitive TRPV3 Channel by Natural Coumarin Osthole for Itch Relief

Abstract

Natural coumarin osthole is a dominant bioactive ingredient of Cnidium monnieri plant that is widely used as traditional Chinese medicine for remedies such as antipruritus and antidermatitis. However, the underlying molecular mechanism of action for osthole remains unknown. In this study we show that osthole exhibits antipruritic effect by selective inhibition of thermosensitive and Ca2+-permeable TRPV3 channels primarily expressed in the keratinocytes of the skin. We utilized the calcium fluorescent assay in FlexStation 3 96-well format and identified coumarin osthole as a selective inhibitor of TRPV3 channels expressed in HEK293 cells or HaCaT keratinocytes. Whole-cell patch clamp recordings further confirmed that osthole selectively inhibited TRPV3 current activated by TRP channel agonist 2-APB (50 µM) in dose-dependent manner with an IC50 value of 34.1 ± 0.7 μM. Behavioral evaluations revealed that inhibition of TRPV3 by osthole or knockout of TRPV3 gene significantly attenuated mouse scratching induced by either acetone-ether-water (AEW) or histamine in localized rostral neck skin. Taken together, our findings identify osthole as a relatively selective blocker of TRPV3, demonstrating a critical role of TRPV3 in chronic itch and also providing a molecular basis for use of coumarin osthole from C. monnieri in anti-pruritic therapy or skin care.