title: Lack of mu-opioid receptor-mediated G-protein activation in the spinal cord of mice lacking Exon 1 or Exons 2 and 3 of the MOR-1 gene.
abstract: The G-protein activation induced by mu-opioid receptor agonists was determined in spinal cord membranes from two types of mu-opioid receptor knockout mice: mice with a disruption of exon 1 (MOR (Exon 1)-KO) or exons 2 and 3 (MOR (Exons 2 and 3)-KO) of the mu-opioid receptor gene. The G-protein activation induced by the opioid agonists was measured by monitoring the increases of guanosine-5'-O-(3-[(35)S]thio)triphosphate ([(35)S]GTP gamma S) binding. The mu-opioid receptor agonists (D-Ala(2),N-MePhe (4),Gly-ol(5)]enkephalin, endomorphin-1, endomorphin-2, morphine, morphine-6 beta-glucuronide, and fentanyl produced concentration-dependent increases of [(35)S]GTP gamma S binding to spinal cord membranes in wild-type mice, but not in MOR (Exon 1)-KO mice or MOR (Exons 2 and 3)-KO mice. On the other hand, the delta-opioid receptor agonist [D-Pen (2,5)]enkephalin, the kappa-opioid receptor agonist (-)U50,488H, or the ORL1-receptor agonist nociception increased [(35)S]GTP gamma S binding in the spinal cord membranes from both MOR (Exon 1)-KO mice and MOR (Exons 2 and 3)-KO mice to the same extent as in the corresponding wild-type mice. The results provide further information about the important roles of the sequences encoded within exon 1 and exons 2 and 3 of mu-opioid receptor gene for the activation of G-proteins by mu-opioid receptor agonists in the mouse spinal cord.
authors.affiliation: Department of Anesthesiology, Medical College of Wisconsin, Milwaukee, USA.
authors.forename: Hirokazu
authors.initials: H
authors.lastname: Mizoguchi
authors.forename: Hsiang-En
authors.initials: HE
authors.lastname: Wu
authors.forename: Minoru
authors.initials: M
authors.lastname: Narita
authors.forename: Ichiro
authors.initials: I
authors.lastname: Sora
authors.forename: Scott F
authors.initials: SF
authors.lastname: Hall
authors.forename: George R
authors.initials: GR
authors.lastname: Uhl
authors.forename: Horace H
authors.initials: HH
authors.lastname: Loh
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagase
authors.forename: Leon F
authors.initials: LF
authors.lastname: Tseng
mesh_terms: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer / Q000494:pharmacology; D000818:Animals; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)- / Q000494:pharmacology; D020881:Enkephalin, D-Penicillamine (2,5)- / Q000494:pharmacology; D005091:Exons; D005283:Fentanyl / Q000494:pharmacology; D019204:GTP-Binding Proteins / Q000819:agonists*; D016244:Guanosine 5'-O-(3-Thiotriphosphate) / Q000378:metabolism; D066298:In Vitro Techniques; D051379:Mice; D018345:Mice, Knockout; D009022:Morphine Derivatives / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology; D018847:Opioid Peptides / Q000494:pharmacology; D011869:Radioligand Assay; D011957:Receptors, Opioid / Q000819:agonists; D017465:Receptors, Opioid, delta / Q000819:agonists; D017473:Receptors, Opioid, kappa / Q000819:agonists; D017450:Receptors, Opioid, mu / Q000819:agonists / Q000235:genetics / Q000502:physiology*; D013116:Spinal Cord / Q000378:metabolism*; D000094942:Nociceptin Receptor; D000097629:Nociceptin
chemical_list: D019900:3,4-Dichloro-N-methyl-N-(2-(1-pyrrolidinyl)-cyclohexyl)-benzeneacetamide, (trans)-Isomer; D020875:Enkephalin, Ala(2)-MePhe(4)-Gly(5)-; D020881:Enkephalin, D-Penicillamine (2,5)-; D005283:Fentanyl; D019204:GTP-Binding Proteins; D016244:Guanosine 5'-O-(3-Thiotriphosphate); D009022:Morphine Derivatives; D009842:Oligopeptides; D018847:Opioid Peptides; D011957:Receptors, Opioid; D017465:Receptors, Opioid, delta; D017473:Receptors, Opioid, kappa; D017450:Receptors, Opioid, mu; D000094942:Nociceptin Receptor; D000097629:Nociceptin; C105293:endomorphin 1; C105294:endomorphin 2; C035349:morphine-6-glucuronide; C000722287:Oprl1 protein, mouse