title: Stargazin and AMPA receptor membrane expression is increased in the somatosensory cortex of Genetic Absence Epilepsy Rats from Strasbourg.
abstract: Absence-like seizures in the Genetic Absence Epilepsy Rats from Strasbourg (GAERS) model are believed to arise in hyperexcitable somatosensory cortical neurons, however the cellular basis of this increased excitability remains unknown. We have previously shown that expression of the Transmembrane AMPA receptor Regulatory Protein (TARP), stargazin, is elevated in the somatosensory cortex of GAERS. TARPs are critical regulators of the trafficking and function of AMPA receptors. Here we examine the developmental expression of stargazin and the impact this may have on AMPA receptor trafficking in the GAERS model. We show that elevated stargazin in GAERS is associated with an increase in AMPA receptor proteins, GluA1 and GluA2 in the somatosensory cortex plasma membrane of adult epileptic GAERS. Elevated stargazin expression is not seen in the epileptic WAG/Rij rat, which is a genetically distinct but phenotypically similar rat model also manifesting absence seizures, indicating that the changes seen in GAERS are unlikely to be a secondary consequence of the seizures. In juvenile (6 week old) GAERS, at the age when seizures are just starting to be expressed, there is elevated stargazin mRNA, but not protein expression for stargazin or the AMPA receptor subunits. In neonatal (7 day old) pre-epileptic GAERS there was no alteration in stargazin mRNA expression in any brain region examined. These data demonstrate that stargazin and AMPA receptor membrane targeting is altered in GAERS, potentially contributing to hyperexcitability in somatosensory cortex, with a developmental time course that would suggest a pathophysiological role in the epilepsy phenotype.
authors.affiliation: Department of Medicine (RMH/WH), University of Melbourne, Melbourne, Australia.
authors.forename: J T T
authors.initials: JT
authors.lastname: Kennard
authors.forename: R
authors.initials: R
authors.lastname: Barmanray
authors.forename: S
authors.initials: S
authors.lastname: Sampurno
authors.forename: E
authors.initials: E
authors.lastname: Ozturk
authors.forename: C A
authors.initials: CA
authors.lastname: Reid
authors.forename: L
authors.initials: L
authors.lastname: Paradiso
authors.forename: G M
authors.initials: GM
authors.lastname: D'Abaco
authors.forename: A H
authors.initials: AH
authors.lastname: Kaye
authors.forename: S J
authors.initials: SJ
authors.lastname: Foote
authors.forename: T J
authors.initials: TJ
authors.lastname: O'Brien
authors.forename: K L
authors.initials: KL
authors.lastname: Powell
mesh_terms: D000818:Animals; D015220:Calcium Channels / Q000096:biosynthesis* / Q000235:genetics; D002462:Cell Membrane / Q000235:genetics / Q000473:pathology / Q000502:physiology; D004195:Disease Models, Animal; D004827:Epilepsy / Q000235:genetics* / Q000473:pathology / Q000503:physiopathology; D020022:Genetic Predisposition to Disease; D009474:Neurons / Q000378:metabolism* / Q000473:pathology / Q000502:physiology; D010641:Phenotype; D051381:Rats; D011922:Rats, Mutant Strains; D018091:Receptors, AMPA / Q000096:biosynthesis* / Q000235:genetics; D013003:Somatosensory Cortex / Q000378:metabolism* / Q000473:pathology / Q000503:physiopathology
chemical_list: C491911:Cacng2 protein, rat; D015220:Calcium Channels; D018091:Receptors, AMPA