title: Hippocampal GluA2 and GluA4 protein but not corresponding mRNA and promoter methylation levels are modulated at retrieval in spatial learning of the rat.
abstract: AMPA receptors mediate most fast excitatory synaptic transmission in the brain. Highly dynamic AMPA receptors are subjected to trafficking, recycling, and/or degradation and replacement. Changes in AMPA receptor abundance is an important mechanism involved in learning and memory formation. Results obtained with the Morris water maze (MWM), a paradigm for testing spatial memory in rodent, correlate with hippocampal synaptic plasticity and NMDA function. Different phases of spatial learning like acquisition and retrieval involve AMPA receptors. Long-term memory formation requires dynamic changes in gene transcription and protein synthesis. It is, however, not known so far if epigenetic marks such as DNA methylation and mRNA levels participate in regulation of AMPA receptors in hippocampus during memory retrieval. In the present study, rats were trained or untrained in the MWM. Steady state levels of hippocampal GluA1-4 mRNA were determined by RT-PCR and promoter methylation levels of GluA1-4 by in-house developed bisulfite pyrosequencing methods. GluA1-4 protein levels were determined in parallel in a membrane fraction by SDS-PAGE followed by Western blotting. Our results indicate that changes of hippocampal membrane AMPA receptors were modulated at the protein level, while no changes were observed at the mRNA and at the promoter methylation level of hippocampal GluA1-4. Training in the MWM at retrieval may, therefore, involve GluA2 and GluA4 subunits that may be regulated by protein stability or trafficking as protein determinations were carried out in a hippocampal membrane fraction.
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Vienna, Austria.
authors.forename: Birgit
authors.initials: B
authors.lastname: Rössner
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Vienna, Austria.
authors.forename: Maximilian
authors.initials: M
authors.lastname: Klingler
authors.affiliation: Department of Pediatrics, Medical University of Vienna, Vienna, Austria.
authors.forename: Tanja
authors.initials: T
authors.lastname: Bulat
authors.affiliation: Department of Pediatrics, Medical University of Vienna, Vienna, Austria.
authors.forename: Ajinkya
authors.initials: A
authors.lastname: Sase
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Vienna, Austria.
authors.forename: Andrea
authors.initials: A
authors.lastname: Zeilinger
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Vienna, Austria.
authors.forename: Melanie
authors.initials: M
authors.lastname: Spitzwieser
authors.affiliation: Department of Pediatrics, Medical University of Vienna, Vienna, Austria.
authors.forename: Jana
authors.initials: J
authors.lastname: Aradska
authors.affiliation: Department of Analytical Chemistry, University of Vienna, Vienna, Austria. margit.cichna@univie.ac.at.
authors.forename: Margit
authors.initials: M
authors.lastname: Cichna-Markl
authors.affiliation: Department of Pharmaceutical Chemistry, Faculty of Life Sciences, University of Vienna, Vienna, Austria. gert.lubec@univie.ac.at.
authors.forename: Gert
authors.initials: G
authors.lastname: Lubec
mesh_terms: D000818:Animals; D019175:DNA Methylation; D044127:Epigenesis, Genetic; D006624:Hippocampus / Q000378:metabolism*; D008297:Male; D018782:Maze Learning / Q000502:physiology*; D008568:Memory / Q000502:physiology*; D009473:Neuronal Plasticity; D011401:Promoter Regions, Genetic; D020033:Protein Isoforms / Q000235:genetics* / Q000378:metabolism; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D018091:Receptors, AMPA / Q000235:genetics* / Q000378:metabolism; D017422:Sequence Analysis, DNA; D009435:Synaptic Transmission
chemical_list: D020033:Protein Isoforms; D012333:RNA, Messenger; D018091:Receptors, AMPA; C104722:glutamate receptor ionotropic, AMPA 2
keywords: AMPA receptor; GluA1; GluA2; GluA3; GluA4; Morris water maze; Spatial memory