title: dextro-Morphine attenuates the morphine-produced conditioned place preference via the sigma(1) receptor activation in the rat.
abstract: An unbiased conditioned place preference paradigm was used to evaluate the effect of dextro-morphine on the morphine-produced reward in male CD rats. Morphine sulfate (1-10 mg/kg) given intraperitoneally dose-dependently produced the conditioned place preference. Pretreatment with dextro-morphine at a dose from 0.1 to 3 microg/kg given subcutaneously dose-dependently attenuated the morphine-produced conditioned place preference. However, dextro-morphine at a higher dose 100 microg/kg did not affect the morphine-produced conditioned place preference. Thus, dextro-morphine pretreatment induces a U-shaped dose-response curve for attenuating the morphine-produced conditioned place preference. The attenuation of the morphine-produced conditioned place preference was reversed by the pretreatment with the sigma(1) receptor antagonist BD1047 (N-[2-(3,4-Dichlorophenyl)ethyl]-N-methyl-2-(dimethylamino)ethylamine dihydrobromide. dextro-Morphine or BD1047 given alone did not affect the baseline place conditioning. It is concluded that dextro-morphine attenuated the morphine-produced conditioned place preference via the sigma(1) receptor activation.
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, Wisconsin 53226, USA.
authors.forename: Hsiang-en
authors.initials: HE
authors.lastname: Wu
authors.forename: Emma T
authors.initials: ET
authors.lastname: Schwasinger
authors.forename: Maia
authors.initials: M
authors.lastname: Terashvili
authors.forename: Leon F
authors.initials: LF
authors.lastname: Tseng
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000704:Analysis of Variance; D000818:Animals; D003216:Conditioning, Operant / Q000187:drug effects*; D004305:Dose-Response Relationship, Drug; D005029:Ethylenediamines; D007274:Injections, Intraperitoneal; D007279:Injections, Subcutaneous; D008297:Male; D009020:Morphine / Q000494:pharmacology*; D051381:Rats; D017480:Receptors, sigma / Q000187:drug effects* / Q000378:metabolism; D012201:Reward; D013237:Stereoisomerism; D000097605:Sigma-1 Receptor
chemical_list: D000701:Analgesics, Opioid; D005029:Ethylenediamines; D009020:Morphine; D017480:Receptors, sigma; D000097605:Sigma-1 Receptor; C097963:N-(2-(3,4-Dichlorphenyl)ethyl)-N,N',N'-trimethyl-1,2-ethandiamin