title: An inducer for glial cell line-derived neurotrophic factor and tumor necrosis factor-alpha protects against methamphetamine-induced rewarding effects and sensitization.
abstract: BACKGROUND
  There are few efficacious medications for drug dependence. We investigated the potential of Leu-Ile, which induces the expression of glial cell line-derived neurotrophic factor (GDNF) and tumor necrosis factor-alpha (TNF-alpha), as a novel therapeutic agent for methamphetamine (METH)-induced dependence.
  
  
  METHODS
  The levels of GDNF and TNF-alpha messenger RNA (mRNA) were determined by real-time reverse transcription polymerase chain reaction. Enzyme immunoassays and immunohistochemistry were employed to determine levels of these proteins. Effects of Leu-Ile on METH-induced rewarding effects and sensitization were investigated with conditioned place preference and locomotor activity tests. Extracellular dopamine (DA) levels and DA uptake into synaptosomes were examined with an in vivo microdialysis and trititated thymidine ([(3)H]) DA uptake assay.
  
  
  RESULTS
  Leu-Ile induced the expression of not only GDNF but also TNF-alpha. Pretreatment with Leu-Ile blocked the acquisition of METH-induced place preference and sensitization. Interestingly, post-treatment with Leu-Ile attenuated them even after their development. An inhibitory effect of Leu-Ile on METH-induced place preference was observed in neither GDNF heterozygous nor TNF-alpha knockout mice. Leu-Ile inhibited DA release in the nucleus accumbens and the decrease in synaptosomal DA uptake in the midbrain induced by repeated METH treatment.
  
  
  CONCLUSIONS
  These results suggest that Leu-Ile inhibits METH-induced rewarding effects and sensitization by regulating extracellular DA levels via the induction of GDNF and TNF-alpha expression.
authors.affiliation: Department of Neuropsychopharmacology and Hospital Pharmacy, Nagoya University Graduate School of Medicine, Nagoya, Japan.
authors.forename: Minae
authors.initials: M
authors.lastname: Niwa
authors.forename: Atsumi
authors.initials: A
authors.lastname: Nitta
authors.forename: Yuichiro
authors.initials: Y
authors.lastname: Yamada
authors.forename: Akira
authors.initials: A
authors.lastname: Nakajima
authors.forename: Kuniaki
authors.initials: K
authors.lastname: Saito
authors.forename: Mitsuru
authors.initials: M
authors.lastname: Seishima
authors.forename: Liya
authors.initials: L
authors.lastname: Shen
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Noda
authors.forename: Shoei
authors.initials: S
authors.lastname: Furukawa
authors.forename: Toshitaka
authors.initials: T
authors.lastname: Nabeshima
mesh_terms: D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal; D000697:Central Nervous System Stimulants / Q000008:administration & dosage*; D003216:Conditioning, Operant / Q000187:drug effects*; D004151:Dipeptides / Q000494:pharmacology*; D004298:Dopamine / Q000378:metabolism; D004305:Dose-Response Relationship, Drug; D004334:Drug Administration Schedule; D004347:Drug Interactions; D004789:Enzyme Activation / Q000187:drug effects; D005786:Gene Expression Regulation / Q000187:drug effects*; D051100:Glial Cell Line-Derived Neurotrophic Factor / Q000172:deficiency / Q000378:metabolism / Q000494:pharmacology; D008297:Male; D008694:Methamphetamine / Q000008:administration & dosage*; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D012333:RNA, Messenger; D020133:Reverse Transcriptase Polymerase Chain Reaction / Q000379:methods; D012201:Reward; D014409:Tumor Necrosis Factor-alpha / Q000172:deficiency / Q000378:metabolism / Q000494:pharmacology
chemical_list: D000697:Central Nervous System Stimulants; D004151:Dipeptides; D051100:Glial Cell Line-Derived Neurotrophic Factor; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; C492946:leucyl-isoleucyl; D008694:Methamphetamine; D004298:Dopamine