title: Up-regulation of dopamine D1 receptor in the hippocampus after establishment of conditioned place preference by cocaine.
abstract: The hippocampus plays an important role in the formation of contextual memory between the environment and the rewarding effect of abused drugs. The dopaminergic neural transmission in the hippocampus seems to be critical for such memory. Using conditioned place preference in rats, we found that the protein level of the dopamine D(1) receptor and its prerequisite mRNA in the hippocampus increased in animals that showed a clear preference for the environment paired with cocaine. The increase was not a simple reflection of the repeated administration of cocaine. Instead, it is attributable to conditioning, because systematic contingency between drug administration and exposure to a particular environment was necessary for the increase. Furthermore, we found that the mRNA of the dopamine D(1) receptors increased in the granule cell layer of the dentate gyrus. These results suggest that the alteration of dopamine D(1) receptor in the hippocampus, especially in the dentate gyrus, is related to the induction of drug-induced contextual memory. The finding implicates the relevance of the dopaminergic signal transduction in the hippocampus to drug dependence.
authors.affiliation: Department of Functional Brain Research, National Institute of Neuroscience, National Center of Neurology and Psychiatry, Tokyo, Japan. t-tomoko@ncnp.go.jp
authors.forename: Tomoko
authors.initials: T
authors.lastname: Tanaka
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kai
authors.forename: Kazuto
authors.initials: K
authors.lastname: Kobayashi
authors.forename: Yuji
authors.initials: Y
authors.lastname: Takano
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Hironaka
mesh_terms: D000818:Animals; D003042:Cocaine / Q000494:pharmacology*; D003213:Conditioning, Psychological / Q000187:drug effects / Q000502:physiology*; D018891:Dentate Gyrus / Q000187:drug effects / Q000378:metabolism; D006624:Hippocampus / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008568:Memory / Q000187:drug effects / Q000502:physiology; D012333:RNA, Messenger / Q000096:biosynthesis; D051381:Rats; D017207:Rats, Sprague-Dawley; D017447:Receptors, Dopamine D1 / Q000096:biosynthesis*; D015854:Up-Regulation / Q000187:drug effects / Q000502:physiology*
chemical_list: D012333:RNA, Messenger; D017447:Receptors, Dopamine D1; D003042:Cocaine