Anti-pruritic and anti-inflammatory effects of natural verbascoside through selective inhibition of temperature-sensitive Ca~(2+)-permeable TRPV3 channel

OBJECTIVE To investigate the molecular mechanism underlying the action of natural verbascoside used as traditional herbal medicine for anti-itch and antiinflammation therapy. METHODS To confirm the inhibitory effect of verbascoside on transient receptor potential(TRP) channels, we performed the whole-cel patch clamp recordings of transiently transfected h TRPs-HEK293 cells. To examine the inhibitory effect of verbascoside on TRPV3 activation-induced itch, thymic stromal lymphopoietin(TSLP) release and proinflammatory response, we adopted a pretreatment by intradermal injection of verbascoside into the mouse neck 30 min before injection of TRPV3 agonist carvacrol into the same site. We counted the bouts of scratching behavior in mice for 30 min and performed q-PCR and Western blotting assay to measure the expression levels of TSLP, inflammatory factors such as tumor necrosis factor(TNF)-α and interleukin(IL)-6 from lysates of mouse neck skin tissues. RESULTS We found that natural verbascoside selectively inhibits TRPV3 in dose-dependent manner over other TRP channels including TRPV1, TRPV4, TRPA1 and TRPM8 channels. Verbascoside attenuates the acute scratching behavior and the release of pruritic mediator TSLP and inflammatory factors TNF-α and IL-6 induced by TRPV3 agonist carvacrol. CONCLUSION Natural verbascoside specifically inhibits TRPV3 channel and alleviates pruritus and inflammation via the channel inhibition. Our observations not only provide a mechanistic explanation for the action of natural verbascoside as herbal medicine used for anti-itch and anti-inflammation therapy, but also demonstrate that specific inhibition of TRPV3 may represent therapeutic strategy for potential treatment of pruritus or dermatitis.