title: Down-regulation of gephyrin and GABAA receptor subunits during epileptogenesis in the CA1 region of hippocampus.
abstract: OBJECTIVE
  Epileptogenesis is the process by which a brain becomes hyperexcitable and capable of generating recurrent spontaneous seizures. In humans, it has been hypothesized that following a brain insult there are a number of molecular and cellular changes that underlie the development of spontaneous seizures. Studies in animal models have shown that an injured brain may develop epileptiform activity before appearance of epileptic seizures and that the pathophysiology accompanying spontaneous seizures is associated with a dysfunction of γ-aminobutyric acid (GABA)ergic neurotransmission. Here, we analyzed the effects of status epilepticus on the expression of GABAA receptors (GABAA Rs) and scaffolding proteins involved in the regulation of GABAA R trafficking and anchoring.
  
  
  METHODS
  Western blot analysis was used to determine the levels of proteins involved in GABAA R trafficking and anchoring in adult rats subjected to pilocarpine-induced status epilepticus (SE) and controls. Cell surface biotinylation using a cell membrane-impermeable reagent was used to assay for changes in the expression of receptors at the plasma membrane. Finally, immunoprecipitation experiments were used to evaluate the composition of GABAA Rs. We examined for a correlation between total GABAA R subunit expression, plasma membrane expression, and receptor composition.
  
  
  RESULTS
  Analysis of tissue samples from the CA1 region of hippocampus show that SE promotes a loss of GABAA R subunits and of the scaffolding proteins associated with them. We also found a decrease in the levels of receptors located at the plasma membrane and alterations in GABAA R composition.
  
  
  CONCLUSIONS
  The changes in protein expression of GABAA Rs and scaffolding proteins detected in these studies provide a potential mechanism to explain the deficits in GABAergic neurotransmission observed during the epileptogenic period. Our current observations represent an additional step toward the elucidation of the molecular mechanisms underlying GABAA R dysfunction during epileptogenesis.
authors.affiliation: Division of Neurology and Translational Epilepsy Research Program, Department of Pediatrics, University of Colorado School of Medicine, Aurora, Colorado, USA. marco.gonzalez@ucdenver.edu
authors.forename: Marco I
authors.initials: MI
authors.lastname: González
authors.forename: Yasmin
authors.initials: Y
authors.lastname: Cruz Del Angel
authors.forename: Amy
authors.initials: A
authors.lastname: Brooks-Kayal
mesh_terms: D000818:Animals; D019921:Biotinylation; D015153:Blotting, Western; D056547:CA1 Region, Hippocampal / Q000378:metabolism*; D002352:Carrier Proteins / Q000096:biosynthesis* / Q000235:genetics; D002462:Cell Membrane / Q000378:metabolism; D015536:Down-Regulation; D004591:Electrophoresis, Polyacrylamide Gel; D004827:Epilepsy / Q000378:metabolism*; D005455:Fluorescent Antibody Technique; D007150:Immunohistochemistry; D047468:Immunoprecipitation; D008297:Male; D008565:Membrane Proteins / Q000096:biosynthesis* / Q000235:genetics; D018613:Microscopy, Confocal; D051381:Rats; D017207:Rats, Sprague-Dawley; D011956:Receptors, Cell Surface / Q000096:biosynthesis; D011963:Receptors, GABA-A / Q000096:biosynthesis* / Q000235:genetics; D013226:Status Epilepticus / Q000139:chemically induced / Q000378:metabolism; D009435:Synaptic Transmission / Q000502:physiology; D005680:gamma-Aminobutyric Acid / Q000502:physiology
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D011956:Receptors, Cell Surface; D011963:Receptors, GABA-A; C073441:gephyrin; D005680:gamma-Aminobutyric Acid