title: Red ginseng extract blocks histamine-dependent itch by inhibition of H1R/TRPV1 pathway in sensory neurons.
abstract: BACKGROUND
  Korean Red Ginseng-a steamed root of Panax ginseng Meyer-has long been used as a traditional medicine in Asian countries. Its antipruritic effect was recently found, but no molecular mechanisms were revealed. Thus, the current study focused on determining the underlying molecular mechanism of Korean Red Ginseng extract (RGE) against histamine-induced itch at the peripheral sensory neuronal level.
  
  
  METHODS
  To examine the antipruritic effect of RGE, we performed in vivo scratching behavior test in mice, as well as in vitro calcium imaging and whole-cell patch clamp experiments to elucidate underlying molecular mechanisms.
  
  
  RESULTS
  The results of our in vivo study confirmed that RGE indeed has an antipruritic effect on histamine-induced scratching in mice. In addition, RGE showed a significant inhibitory effect on histamine-induced responses in primary cultures of mouse dorsal root ganglia, suggesting that RGE has a direct inhibitory effect on sensory neuronal level. Results of further experiments showed that RGE inhibits histamine-induced responses on cells expressing both histamine receptor subtype 1 and TRPV1 ion channel, indicating that RGE blocks the histamine receptor type 1/TRPV1 pathway in sensory neurons, which is responsible for histamine-dependent itch sensation.
  
  
  CONCLUSIONS
  The current study found for the first time that RGE effectively blocks histamine-induced itch in peripheral sensory neurons. We believe that the current results will provide an insight on itch transmission and will be helpful in understanding how RGE exerts its antipruritic effects.
authors.affiliation: Sensory Research Center, Creative Research Initiatives, College of Pharmacy, Seoul National University, Seoul, Korea ; Department of Psychiatry and Program in Neuroscience, McLean Hospital, Harvard Medical School, Belmont, MA, USA.
authors.forename: Yongwoo
authors.initials: Y
authors.lastname: Jang
authors.affiliation: College of Pharmacy, Gachon University, Incheon, Korea.
authors.forename: Wook-Joo
authors.initials: WJ
authors.lastname: Lee
authors.affiliation: Sensory Research Center, Creative Research Initiatives, College of Pharmacy, Seoul National University, Seoul, Korea.
authors.forename: Gyu-Sang
authors.initials: GS
authors.lastname: Hong
authors.affiliation: College of Pharmacy, Gachon University, Incheon, Korea.
authors.forename: Won-Sik
authors.initials: WS
authors.lastname: Shim
keywords: H1R; Korean Red Ginseng extract; TRPV1; histamine; itch