title: Analgesic Effects of Toad Cake and Toad-cake-containing Herbal Drugs: Analgesic effects of toad cake.
abstract: OBJECTIVE
  This study was conducted to clarify the analgesic effect of toad cake and toad-cake-containing herbal drugs.
  
  
  METHODS
  We counted the writhing response of mice after the intraperitoneal administration of acetic acid as a nociceptive pain model and the withdrawal response after the plantar surface stimulation of the hind paw induced by partial sciatic nerve ligation of the mice as a neuropathic pain model to investigate the analgesic effect of toad cake and toad-cake-containing herbal drugs. A co-treatment study with serotonin biosynthesis inhibitory drug 4-chloro- DL-phenylalanine methyl ester hydrochloride (PCPA), the catecholamine biosynthesis inhibitory drug α-methyl- DL-tyrosine methyl ester hydrochloride (AMPT) or the opioid receptor antagonist naloxone hydrochloride was also conducted.
  
  
  RESULTS
  Analgesic effects in a mouse model of nociceptive pain and neuropathic pain were shown by oral administration of toad cake and toad-cake-containing herbal drugs. The effects of toad cake and toad-cake-containing herbal drugs disappeared upon co-treatment with PCPA, but not with AMPT or naloxone in the nociceptive pain model; the analgesic effect of toad-cake-containing herbal drugs also disappeared upon co-treatment with PCPA in the neuropathic pain model.
  
  
  CONCLUSIONS
  Toad cake and toad-cake-containing herbal drugs have potential for the treatments of nociceptive pain and of neuropathic pain, such as post-herpetic neuralgia, trigeminal neuralgia, diabetic neuralgia, and postoperative or posttraumatic pain, by activation of the central serotonin nervous system.
authors.affiliation: Tokyo Research Center, Kyushin Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Inoue
authors.affiliation: Tokyo Research Center, Kyushin Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Shimizu
authors.affiliation: Tokyo Research Center, Kyushin Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Ryo
authors.initials: R
authors.lastname: Masui
authors.affiliation: Tokyo Research Center, Kyushin Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Tomomi
authors.initials: T
authors.lastname: Usui
authors.affiliation: Tokyo Research Center, Kyushin Pharmaceutical Co., Ltd., Tokyo, Japan.
authors.forename: Keiichi
authors.initials: K
authors.lastname: Sudoh
keywords: neuropathic pain; nociceptive pain; serotonin; toad cake