title: Behavioral effects of elevated expression of human equilibrative nucleoside transporter 1 in mice.
abstract: Adenosine concentrations are regulated by purinergic enzymes and nucleoside transporters. Transgenic mice with neuronal expression of human equilibrative nucleoside transporter 1 (hENT1) have been generated (Parkinson et al., 2009 [7]). The present study tested the hypothesis that mice homozygous and heterozygous for the transgene exhibit differences in hENT1 mRNA and protein expression, and in behavioral responses to caffeine and ethanol, two drugs with adenosine-dependent actions. Real time polymerase chain reaction (PCR) was used to identify mice heterozygous and homozygous for the transgene. Gene expression, determined by real time PCR of cDNA reverse transcribed from cerebral cortex RNA, was 3.8-fold greater in homozygous mice. Protein abundance, determined by radioligand binding assays using 0.14nM [(3)H]S-(4-nitrobenzyl)-6-thioinosine ([(3)H]NBTI), was up to 84% greater in cortex synaptosome membranes from homozygous than from heterozygous mice. In western blots with an antibody specific for hENT1, a protein of approximately 40kDa was strongly labelled in cortex samples from homozygous mice, weakly labelled in samples from heterozygous mice and absent from samples from wild type mice. In behavioral assays, transgenic mice showed a greater response to ethanol and a reduced response to caffeine than wild type littermates; however, no significant differences between heterozygous and homozygous mice were detected. These data indicate that the difference in ENT1 function between wild type and heterozygous mice was greater than that between heterozygous and homozygous mice. Therefore, either heterozygous or homozygous hENT1 transgenic mice can be used in studies of ENT1 regulation of adenosine levels and adenosine dependent behaviors.
authors.affiliation: Department of Pharmacology and Therapeutics, University of Manitoba, Winnipeg, Manitoba R3E 0T6, Canada.
authors.forename: Sara
authors.initials: S
authors.lastname: Kost
authors.forename: Chao
authors.initials: C
authors.lastname: Sun
authors.forename: Wei
authors.initials: W
authors.lastname: Xiong
authors.forename: Kathryn
authors.initials: K
authors.lastname: Graham
authors.forename: Carol E
authors.initials: CE
authors.lastname: Cass
authors.forename: James D
authors.initials: JD
authors.lastname: Young
authors.forename: Benedict C
authors.initials: BC
authors.lastname: Albensi
authors.forename: Fiona E
authors.initials: FE
authors.lastname: Parkinson
mesh_terms: D000248:Adenosine Kinase / Q000235:genetics / Q000378:metabolism; D000704:Analysis of Variance; D000818:Animals; D001522:Behavior, Animal / Q000187:drug effects / Q000502:physiology*; D002110:Caffeine / Q000494:pharmacology; D002540:Cerebral Cortex / Q000378:metabolism; D033721:Equilibrative Nucleoside Transporter 1 / Q000235:genetics / Q000378:metabolism*; D000431:Ethanol / Q000494:pharmacology; D005786:Gene Expression Regulation / Q000235:genetics*; D006801:Humans; D051379:Mice; D008822:Mice, Transgenic; D009043:Motor Activity / Q000187:drug effects / Q000235:genetics; D011485:Protein Binding / Q000187:drug effects / Q000235:genetics; D013868:Thioinosine / Q000031:analogs & derivatives / Q000493:pharmacokinetics; D014316:Tritium / Q000493:pharmacokinetics
chemical_list: D033721:Equilibrative Nucleoside Transporter 1; C438649:SLC29A1 protein, human; D014316:Tritium; D002110:Caffeine; D000431:Ethanol; D013868:Thioinosine; D000248:Adenosine Kinase; C001789:4-nitrobenzylthioinosine