title: Type 1 equilibrative nucleoside transporter regulates ethanol drinking through accumbal N-methyl-D-aspartate receptor signaling.
abstract: BACKGROUND
  Mice lacking type 1 equilibrative nucleoside transporter (ENT1(-/-)) exhibit increased ethanol-preferring behavior compared with wild-type littermates. This phenotype of ENT1(-/-) mice appears to be correlated with increased glutamate levels in the nucleus accumbens (NAc). However, little is known about the downstream consequences of increased glutamate signaling in the NAc.
  
  
  METHODS
  To investigate the significance of the deletion of ENT1 and its effect on glutamate signaling in the NAc, we employed microdialysis and iTRAQ proteomics. We validated altered proteins using Western blot analysis. We then examined the pharmacological effects of the inhibition of the N-methyl-D-aspartate (NMDA) glutamate receptor and protein kinase Cγ (PKCγ) on alcohol drinking in wild-type mice. In addition, we investigated in vivo cyclic adenosine monophosphate response element binding activity using cyclic adenosine monophosphate response element-β-galactosidase mice in an ENT1(-/-) background.
  
  
  RESULTS
  We identified that NMDA glutamate receptor-mediated downregulation of intracellular PKCγ-neurogranin-calcium-calmodulin dependent protein kinase type II signaling is correlated with reduced cyclic adenosine monophosphate response element binding activity in ENT1(-/-) mice. Inhibition of PKCγ promotes ethanol drinking in wild-type mice to levels similar to those of ENT1(-/-) mice. In contrast, an NMDA glutamate receptor antagonist reduces ethanol drinking of ENT1(-/-) mice.
  
  
  CONCLUSIONS
  These findings demonstrate that the genetic deletion or pharmacological inhibition of ENT1 regulates NMDA glutamate receptor-mediated signaling in the NAc, which provides a molecular basis that underlies the ethanol-preferring behavior of ENT1(-/-) mice.
authors.affiliation: Department of Molecular Pharmacology and Experimental Therapeutics, Mayo Clinic College of Medicine, Rochester, Minnesota 55905, USA.
authors.forename: Hyung Wook
authors.initials: HW
authors.lastname: Nam
authors.forename: Moonnoh R
authors.initials: MR
authors.lastname: Lee
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhu
authors.forename: Jinhua
authors.initials: J
authors.lastname: Wu
authors.forename: David J
authors.initials: DJ
authors.lastname: Hinton
authors.forename: Sun
authors.initials: S
authors.lastname: Choi
authors.forename: Taehyun
authors.initials: T
authors.lastname: Kim
authors.forename: Nora
authors.initials: N
authors.lastname: Hammack
authors.forename: Jerry C P
authors.initials: JC
authors.lastname: Yin
authors.forename: Doo-Sup
authors.initials: DS
authors.lastname: Choi
mesh_terms: D015763:2-Amino-5-phosphonovalerate / Q000031:analogs & derivatives / Q000494:pharmacology; D000428:Alcohol Drinking / Q000378:metabolism*; D000704:Analysis of Variance; D000818:Animals; D015153:Blotting, Western; D017362:Cyclic AMP Response Element-Binding Protein / Q000378:metabolism; D033721:Equilibrative Nucleoside Transporter 1 / Q000235:genetics / Q000378:metabolism*; D000431:Ethanol / Q000008:administration & dosage; D018691:Excitatory Amino Acid Antagonists / Q000494:pharmacology; D018698:Glutamic Acid / Q000378:metabolism; D008297:Male; D051379:Mice; D018345:Mice, Knockout; D017551:Microdialysis; D009714:Nucleus Accumbens / Q000187:drug effects / Q000378:metabolism*; D011493:Protein Kinase C / Q000037:antagonists & inhibitors / Q000378:metabolism; D016194:Receptors, N-Methyl-D-Aspartate / Q000378:metabolism*; D012646:Self Administration; D015398:Signal Transduction / Q000187:drug effects / Q000502:physiology
chemical_list: D017362:Cyclic AMP Response Element-Binding Protein; D033721:Equilibrative Nucleoside Transporter 1; D018691:Excitatory Amino Acid Antagonists; D016194:Receptors, N-Methyl-D-Aspartate; C064539:2-amino-4-methyl-5-phosphono-3-pentenoic acid; D000431:Ethanol; D018698:Glutamic Acid; D015763:2-Amino-5-phosphonovalerate; D011493:Protein Kinase C