title: Ignavine: a novel allosteric modulator of the μ opioid receptor.
abstract: Processed Aconiti tuber (PAT) is used to treat pain associated with various disorders. Although it has been demonstrated that the κ opioid receptor (KOR) signaling pathway is a mediator of the analgesic effect of PAT, active components affecting opioid signaling have not yet been identified. In this study, we explored candidate components of PAT by pharmacokinetic analysis and identified ignavine, which is a different structure from aconitine alkaloids. A receptor binding assay of opioid receptors showed that ignavine specifically binds the μ opioid receptor (MOR), not the KOR. Receptor internalization assay in MOR-expressing cell lines revealed that ignavine augmented the responses produced by D-Ala(2)-N-Me-Phe(4)-Gly-ol(5)-enkephalin (DAMGO), a representative MOR agonist, at a low concentration and inhibited it at a higher concentration. Ignavine also exerted positive modulatory activity for DAMGO, endomorphin-1 and morphine in cAMP assay. Additionally, ignavine alone showed an analgesic effect in vivo. In silico simulation analysis suggested that ignavine would induce a unique structural change distinguished from those induced by a representative MOR agonist and antagonist. These data collectively suggest the possibility that ignavine could be a novel allosteric modulator of the MOR. The present results may open the way for the development of a novel pain management strategy.
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.|Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Katsuya
authors.initials: K
authors.lastname: Ohbuchi
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.|Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Chika
authors.initials: C
authors.lastname: Miyagi
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Suzuki
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.
authors.forename: Yasuharu
authors.initials: Y
authors.lastname: Mizuhara
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Mizuno
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.
authors.forename: Yuji
authors.initials: Y
authors.lastname: Omiya
authors.affiliation: Tsumura Research Laboratories, Tsumura and Co., 3586 Yoshiwara, Ami-machi Inashiki-gun, Ibaraki 300-1192, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Yamamoto
authors.affiliation: Environmental Molecular Biology Laboratory, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi, Ibaraki 305-8575, Japan.
authors.forename: Eiji
authors.initials: E
authors.lastname: Warabi
authors.affiliation: Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.|Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-0022, Japan.
authors.forename: Yuka
authors.initials: Y
authors.lastname: Sudo
authors.affiliation: Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.|Molecular Pathology and Metabolic Disease, Faculty of Pharmaceutical Sciences, Tokyo University of Science, 2641 Yamazaki, Noda-shi, Chiba 278-0022, Japan.
authors.forename: Akinobu
authors.initials: A
authors.lastname: Yokoyama
authors.affiliation: Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Kanako
authors.initials: K
authors.lastname: Miyano
authors.affiliation: Molecular Profiling Research Center for Drug Discovery, AIST Tokyo Waterfront Bio-IT Research Building 2-4-7 Aomi, Koto-ku, Tokyo 135-0064, Japan.|Dicision of Biomedical Science, Faculty of Medicine, University of Tsukuba, 1-1-1 Tennodai, Tsukuba-shi, Ibaraki 305-8575, Japan.
authors.forename: Takatsugu
authors.initials: T
authors.lastname: Hirokawa
authors.affiliation: Division of Cancer Pathophysiology, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.|Division of Supportive Care Research, National Cancer Center Research Institute, 5-1-1 Tsukiji, Chuo-ku, Tokyo 104-0045, Japan.
authors.forename: Yasuhito
authors.initials: Y
authors.lastname: Uezono
mesh_terms: D000157:Aconitine / Q000737:chemistry / Q000493:pharmacokinetics / Q000494:pharmacology; D000494:Allosteric Regulation / Q000187:drug effects; D000818:Animals; D002460:Cell Line; D004305:Dose-Response Relationship, Drug; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000187:drug effects*; D008297:Male; D059408:Pain Management / Q000379:methods; D051381:Rats; D017207:Rats, Sprague-Dawley; D017450:Receptors, Opioid, mu / Q000096:biosynthesis* / Q000235:genetics
chemical_list: D017450:Receptors, Opioid, mu; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; C035745:ignavine; D000157:Aconitine