title: Traditional Japanese medicines inhibit compound action potentials in the frog sciatic nerve.
abstract: BACKGROUND
  Traditional Japanese (Kampo) medicines have a variety of clinical effects including pain alleviation, but evidence for a mechanism for their pain relief has not yet been elucidated fully. Considering that Kampo medicine contains many plant-derived chemicals having an ability to inhibit nerve action potential conduction, it is possible that this medicine inhibits nerve conduction. The purpose of the present study was to know how various Kampo medicines affect nerve conduction.
  
  
  METHODS
  We examined the effects of Kampo and crude medicines on compound action potentials (CAPs) recorded from the frog sciatic nerve by using the air-gap method.
  
  
  RESULTS
  Daikenchuto, rikkosan, kikyoto, rikkunshito, shakuyakukanzoto and kakkonto concentration-dependently reduced the peak amplitude of the CAP. Among the Kampo medicines, daikenchuto was the most effective in inhibiting CAPs. Daikenchuto is composed of three kinds of crude medicine, Japanese pepper, processed ginger and ginseng radix. When the crude medicines were tested, Japanese pepper and processed ginger reduced CAP peak amplitudes, while ginseng radix hardly affected CAPs. Moreover, there was an interaction between the Japanese pepper and processed ginger activities in such that one medicine at low but not high concentrations increased the extent of the inhibition by the other one that was co-applied.
  
  
  CONCLUSIONS
  Kampo medicines have an ability to inhibit nerve conduction. This action of daikenchuto is due to Japanese pepper and processed ginger but not ginseng radix, probably through an interaction between Japanese pepper and processed ginger in a manner dependent on their concentrations. Nerve conduction inhibition could contribute to at least a part of Kampo medicine's clinical effects such as pain alleviation.
authors.affiliation: Department of Physiology, Saga Medical School, Saga, Japan. Electronic address: ak10wx48@gmail.com.
authors.forename: Akitomo
authors.initials: A
authors.lastname: Matsushita
authors.affiliation: Department of Physiology, Saga Medical School, Saga, Japan. Electronic address: fujitat@cc.saga-u.ac.jp.
authors.forename: Tsugumi
authors.initials: T
authors.lastname: Fujita
authors.affiliation: Department of Physiology, Saga Medical School, Saga, Japan. Electronic address: t0m3nyag0@yahoo.co.jp.
authors.forename: Sena
authors.initials: S
authors.lastname: Ohtsubo
authors.affiliation: Department of Physiology, Saga Medical School, Saga, Japan.
authors.forename: Eiichi
authors.initials: E
authors.lastname: Kumamoto
mesh_terms: D000200:Action Potentials / Q000187:drug effects*; D000818:Animals; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal / Q000494:pharmacology*; D020939:Zingiber officinale / Q000737:chemistry; D006035:Glycyrrhiza; D007564:Japan; D020835:Medicine, Kampo / Q000379:methods; D008519:Medicine, Traditional / Q000379:methods; D009431:Neural Conduction / Q000187:drug effects*; D029596:Paeonia; D005894:Panax / Q000737:chemistry; D010936:Plant Extracts / Q000494:pharmacology; D011898:Ranidae; D012584:Sciatic Nerve / Q000187:drug effects*; D032106:Zanthoxylum / Q000737:chemistry; D030521:Zingiberaceae
chemical_list: D004338:Drug Combinations; D004365:Drugs, Chinese Herbal; D010936:Plant Extracts; C121414:dai-kenchu-to; C090831:kakkon-to; C502433:rikko-san; C038462:shakuyaku-kanzoh-toh
keywords: Compound action potential; Daikenchuto; Japanese pepper; Kampo medicine; Processed ginger; Sciatic nerve