title: Differential effects of morphine, DPDPE, and U-50488 on apomorphine-induced climbing behavior in mu-opioid receptor knockout mice.
abstract: The present study examined the hypothesis whether the opioid receptors (mu, delta, and kappa) contribute to a behavioral dopaminergic activation produced by dopamine receptor agonist, apomorphine, by comparing responses in wild type and mu-opioid receptor knockout mice. The data suggest that expression of mu-opioid receptors plays an important role in the enhancement of climbing behavior induced by apomorphine. Compared to wild type mice, a response in the dopaminergic behavior by treatment with delta-receptor agonist, DPDPE, is more sensitive to the mice lacking mu-opioid receptor. Treatment with kappa-receptor agonist, U-50488, is potentiated the apomorphine-induced climbing behavior in wild type and mu-opioid receptor knockout mice. These responses may be independent of that through mu-opioid receptors. Therefore, the our results show that dopaminergic activation measured by climbing behavior in mu-opioid receptors knockout mice are differently regulated by mu-, delta-, and kappa-opioid receptor agonists.
authors.affiliation: Department of Pharmacology College of Pharmacy, Sungkyunkwan University, 440-746, Suwon, South Korea. jang@skku.ac.kr
authors.forename: C G
authors.initials: CG
authors.lastname: Jang
authors.forename: S Y
authors.initials: SY
authors.lastname: Lee
authors.forename: Y
authors.initials: Y
authors.lastname: Park
authors.forename: T
authors.initials: T
authors.lastname: Ma
authors.forename: H H
authors.initials: HH
authors.lastname: Loh
authors.forename: I K
authors.initials: IK
authors.lastname: Ho
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology*; D018712:Analgesics, Non-Narcotic / Q000494:pharmacology*; D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001058:Apomorphine / Q000494:pharmacology; D018491:Dopamine Agonists / Q000494:pharmacology; D020881:Enkephalin, D-Penicillamine (2,5)- / Q000494:pharmacology*; D005260:Female; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects*; D017450:Receptors, Opioid, mu / Q000235:genetics*
chemical_list: D018712:Analgesics, Non-Narcotic; D000701:Analgesics, Opioid; D018491:Dopamine Agonists; D017450:Receptors, Opioid, mu; D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D009020:Morphine; D020881:Enkephalin, D-Penicillamine (2,5)-; D001058:Apomorphine