title: Dopamine D3 receptor knock-out mice display deficits in locomotor sensitization after chronic morphine administration.
abstract: Locomotor sensitization is the progressive and enduring enhancement of locomotion induced by stimulants such as drugs, which alter rodent locomotion in a long-standing manner. The dopamine D3 receptor has been reported to play a role in morphine addiction. The aim of the present study was to investigate the role of dopamine D3 receptor in the morphine induced locomotor sensitization using dopamine D3 receptor knock-out mice. The dopamine D3 receptor knock-out mice did not display an enhanced behavioral response to acute morphine administration or develop an increased rate of locomotor sensitization to intermittent morphine administration. When 2mg/kg naloxone was co-administered with 10mg/kg morphine, morphine-induced locomotion sensitization in wild-type mice was significantly blocked while the locomotion in the D3 receptor knock-out mice was decreased. Then the wild-type mice were administered with dopamine D3 antagonist nafadotride. It was found that co-administration of morphine with nafadotride could effectively suppress the level of morphine induced behavioral sensitization. It was concluded that a loss of the dopamine D3 receptor gene may inhibit acute morphine induced hyperlocomotor activity and chronic morphine induced behavioral sensitization.
authors.affiliation: Forensic Department, Xi'an Jiaotong University School of Medicine, 76# West Yanta Road, Xi'an, Shaanxi 710061, PR China. Litao050428@mail.xjtu.edu.cn
authors.forename: Tao
authors.initials: T
authors.lastname: Li
authors.forename: Ying
authors.initials: Y
authors.lastname: Hou
authors.forename: Chun-xia
authors.initials: CX
authors.lastname: Yan
authors.forename: Teng
authors.initials: T
authors.lastname: Chen
authors.forename: Yan
authors.initials: Y
authors.lastname: Zhao
authors.forename: Sheng-bing
authors.initials: SB
authors.lastname: Li
mesh_terms: D000701:Analgesics, Opioid / Q000494:pharmacology*; D000818:Animals; D018492:Dopamine Antagonists / Q000494:pharmacology; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D009020:Morphine / Q000494:pharmacology*; D009043:Motor Activity / Q000187:drug effects* / Q000502:physiology*; D009270:Naloxone / Q000494:pharmacology; D009281:Naphthalenes / Q000494:pharmacology; D009292:Narcotic Antagonists / Q000494:pharmacology; D011759:Pyrrolidines / Q000494:pharmacology; D050637:Receptors, Dopamine D3 / Q000037:antagonists & inhibitors / Q000235:genetics / Q000502:physiology*; D020133:Reverse Transcriptase Polymerase Chain Reaction
chemical_list: D000701:Analgesics, Opioid; D018492:Dopamine Antagonists; D009281:Naphthalenes; D009292:Narcotic Antagonists; D011759:Pyrrolidines; D050637:Receptors, Dopamine D3; D009270:Naloxone; D009020:Morphine; C097285:nafadotride