title: Morphine tolerance and dependence in the nociceptin receptor knockout mice.
abstract: Here we report the involvement of nociceptin receptor in tolerance to morphine-induced antinociception and in morphine dependence. There was no different nociceptive perception and antinociceptive effects of morphine between wild-type and the nociceptin receptor knockout mice. Tolerance to morphine (10 mg/kg)-induced antinociception was developed in both wild-type and the nociceptin receptor knockout mice after administration of morphine (10 mg/kg) twice a day for 5 days. When naloxone (5 mg/kg) was administered to mice treated with morphine repeatedly on the 6th day, morphine withdrawal syndrome was observed in both wild-type and the nociceptin receptor knockout mice, which were accompanied by the elevation of cyclic AMP levels. While naloxone benzoylhydrazone (1 mg/kg), a putative antagonist for nociceptin receptor/naloxone benzoylhydrazone-sensitive sites, also induced the morphine withdrawal signs in both wild-type and the nociceptin receptor knockout mice, the jumping signs in the nociceptin receptor knockout mice were less severe than those in wild-type mice. Treatment with naloxone benzoylhydrazone in morphine-dependent wild-type mice caused a significant increase in cyclic AMP levels in the thalamus while it had no effect in the nociceptin receptor knockout mice. The analysis of opioid mu-receptor binding showed no difference between wild-type and the nociceptin receptor knockout mice. These results suggest that the nociceptin receptor/naloxone benzoylhydrazone-sensitive sites contribute to the induction of morphine withdrawal syndrome in part. Furthermore, it is demonstrated that morphine withdrawal syndrome excepting jumping can be induced by naloxone benzoylhydrazone without any changes in the cyclic AMP levels in the thalamus.
authors.affiliation: Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: T
authors.initials: T
authors.lastname: Mamiya
authors.forename: Y
authors.initials: Y
authors.lastname: Noda
authors.forename: X
authors.initials: X
authors.lastname: Ren
authors.forename: T
authors.initials: T
authors.lastname: Nagai
authors.forename: H
authors.initials: H
authors.lastname: Takeshima
authors.forename: M
authors.initials: M
authors.lastname: Ukai
authors.forename: T
authors.initials: T
authors.lastname: Nabeshima
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology; D001921:Brain / Q000187:drug effects / Q000378:metabolism* / Q000503:physiopathology; D000242:Cyclic AMP / Q000378:metabolism; D004334:Drug Administration Schedule; D004361:Drug Tolerance / Q000502:physiology*; D051379:Mice; D018345:Mice, Knockout; D009020:Morphine / Q000494:pharmacology*; D009021:Morphine Dependence / Q000378:metabolism* / Q000503:physiopathology; D009043:Motor Activity / Q000187:drug effects / Q000502:physiology; D009270:Naloxone / Q000031:analogs & derivatives* / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D010146:Pain / Q000378:metabolism* / Q000503:physiopathology; D010147:Pain Measurement / Q000187:drug effects; D011869:Radioligand Assay; D011957:Receptors, Opioid / Q000172:deficiency* / Q000235:genetics; D013375:Substance Withdrawal Syndrome / Q000378:metabolism / Q000503:physiopathology; D000094942:Nociceptin Receptor
chemical_list: D000701:Analgesics, Opioid; D009292:Narcotic Antagonists; D011957:Receptors, Opioid; C058380:naloxone benzoylhydrazone; D009270:Naloxone; D009020:Morphine; D000242:Cyclic AMP; D000094942:Nociceptin Receptor; C000722287:Oprl1 protein, mouse