title: Effects of mitragynine on cAMP formation mediated by delta-opiate receptors in NG108-15 cells.
abstract: Mitragynine, a major constituent of the young leaves of Mitragyna speciosa KORTH., has been reported to exert antinociceptive activity in mice. To determine the mechanism the influence of mitragynine on cAMP content was measured in NG108-15 cells which possess delta opioid receptors and alpha 2B-adrenoceptors. Mitragynine inhibited the forskolin-stimulated cAMP content in a concentration dependent manner as well as morphine and noradrenaline. Mitragynine- and morphine-induced inhibition of cAMP content were blocked by naloxone. Although idazoxane inhibited noradrenaline-induced inhibition of the cAMP content, idazoxane had no effect on mitragynine-induced inhibition. These results suggest that mitragynine acts directly on opioid receptors, but not on alpha 2-adrenoceptors, to show antinociceptive activity.
authors.affiliation: Division of Pharmacology, Research Institute of Wakan-yaku (Oriental Medicines), Toyama Medical and Pharmaceutical University, Japan.
authors.forename: M
authors.initials: M
authors.lastname: Tohda
authors.forename: S
authors.initials: S
authors.lastname: Thongpraditchote
authors.forename: K
authors.initials: K
authors.lastname: Matsumoto
authors.forename: Y
authors.initials: Y
authors.lastname: Murakami
authors.forename: S
authors.initials: S
authors.lastname: Sakai
authors.forename: N
authors.initials: N
authors.lastname: Aimi
authors.forename: H
authors.initials: H
authors.lastname: Takayama
authors.forename: P
authors.initials: P
authors.lastname: Tongroach
authors.forename: H
authors.initials: H
authors.lastname: Watanabe
mesh_terms: D000700:Analgesics / Q000494:pharmacology*; D000242:Cyclic AMP / Q000037:antagonists & inhibitors*; D000077743:Diterpene Alkaloids; D018341:Receptors, Adrenergic, alpha-2 / Q000502:physiology; D017465:Receptors, Opioid, delta / Q000502:physiology*; D046948:Secologanin Tryptamine Alkaloids / Q000494:pharmacology*; D014407:Tumor Cells, Cultured / Q000378:metabolism
chemical_list: D000700:Analgesics; D000077743:Diterpene Alkaloids; D018341:Receptors, Adrenergic, alpha-2; D017465:Receptors, Opioid, delta; D046948:Secologanin Tryptamine Alkaloids; D000242:Cyclic AMP; C001801:mitragynine