title: Stereoselective action of (+)-morphine over (-)-morphine in attenuating the (-)-morphine-produced antinociception via the naloxone-sensitive sigma receptor in the mouse.
abstract: We have previously demonstrated that (+)-morphine and (-)-morphine given spinally stereoselectively attenuate the spinally-administered (-)-morphine-produced tail-flick inhibition in the mouse. The phenomenon has been defined as antianalgesia. Present studies were then undertaken to determine if the systemic administration of (+)-morphine and (-)-morphine also stereoselectively attenuates the systemic (-)-morphine-produced tail-flick inhibition and the effects of (+)-morphine and (-)-morphine are mediated by the naloxone-sensitive sigma receptor activation in male CD-1 mice. Pretreatment with (+)-morphine at a dose of 0.01-10 ng/kg given subcutaneously dose-dependently attenuated the tail-flick inhibition produced by subcutaneously-administered (-)-morphine (5 mg/kg). Pretreatment with (-)-morphine (0.01-1.0 mg/kg) given subcutaneously also attenuates the (-)-morphine-produced tail-flick inhibition. The ED50 values for (+)-morphine and (-)-morphine for inhibiting the (-)-morphine-produced tail-flick inhibition were estimated to be 30.6 pg/kg and 97.5 microg/kg, respectively. The attenuation of the (-)-morphine-produced tail-flick inhibition induced by (+)-morphine or (-)-morphine pretreatment was reversed by the pretreatment with (+)-naloxone or by the sigma receptor antagonist BD1047 (N-[2-(3,4-dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine dihydrobromide) given subcutaneously. Pretreatment with (+)-pentazocine, a selective sigma receptor agonist, (1-10 mg/kg) given subcutaneously also attenuates (-)-morphine-produced tail-flick inhibition, which was restored by (+)-naloxone (4 mg/kg) or BD1047 (10 mg/kg) pretreated subcutaneously. It is concluded that (+)-morphine exhibits extremely high stereoselective action over (-)-morphine given systemically in attenuating the systemic (-)-morphine-produced antinociception and the antianalgesic effect of (+)-morphine and (-)-morphine is mediated by activation of the naloxone-sensitive sigma receptor.
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, WI 53226, USA.
authors.forename: Hsiang-en
authors.initials: HE
authors.lastname: Wu
authors.forename: Jau-Shyong
authors.initials: JS
authors.lastname: Hong
authors.forename: Leon F
authors.initials: LF
authors.lastname: Tseng
mesh_terms: D000701:Analgesics, Opioid / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D000818:Animals; D004305:Dose-Response Relationship, Drug; D005029:Ethylenediamines / Q000494:pharmacology; D007279:Injections, Subcutaneous; D008297:Male; D051379:Mice; D009020:Morphine / Q000008:administration & dosage / Q000737:chemistry / Q000494:pharmacology* / Q000627:therapeutic use; D009270:Naloxone / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010146:Pain / Q000378:metabolism / Q000503:physiopathology / Q000517:prevention & control*; D010147:Pain Measurement; D017288:Pain Threshold / Q000187:drug effects*; D010423:Pentazocine / Q000494:pharmacology; D017480:Receptors, sigma / Q000187:drug effects* / Q000378:metabolism; D013237:Stereoisomerism
chemical_list: D000701:Analgesics, Opioid; D005029:Ethylenediamines; D009292:Narcotic Antagonists; D017480:Receptors, sigma; C097963:N-(2-(3,4-Dichlorphenyl)ethyl)-N,N',N'-trimethyl-1,2-ethandiamin; D009270:Naloxone; D009020:Morphine; D010423:Pentazocine