title: Spontaneous synaptic activity in an organotypic culture of the mouse retina.
abstract: OBJECTIVE
  Many strains of mutant mice die at birth, when the retina is still very immature. The retinas of such mice can be studied in organotypic cultures. After a preceding anatomic study of the synaptic development, the electrical activity of the synaptic circuits within such cultures was studied in wild-type and gephyrin-deficient mice.
  
  
  METHODS
  Organotypic cultures of newborn mouse retinas were grown for 14 days in vitro. Spontaneous postsynaptic currents (sPSCs) of amacrine cells were measured by using the whole-cell configuration of the patch-clamp technique. GABAergic and glycinergic currents that were isolated with specific antagonists, and retinas from wild-type (geph(+/+)) and gephyrin-deficient (geph(-/-)) mice were compared.
  
  
  RESULTS
  Rapidly decaying sPSCs that were blocked by kynurenic acid were mediated by ionotropic glutamate receptors, whereas sPSCs with significantly higher peak amplitudes and slow-decay kinetics were identified as spontaneous inhibitory postsynaptic currents (sIPSCs) mediated by gamma-aminobutyric acid type A receptors (GABA(A)Rs) and glycine receptors (GlyRs). In gephyrin-deficient (geph(-/-)) cultures, we found no sIPSCs mediated by GlyRs. sIPSCs mediated by GABA(A)Rs expressed in amacrine cells of geph(-/-) retinas decayed significantly faster than GABAergic sIPSCs recorded in amacrine cells of geph(+/+) retinas.
  
  
  CONCLUSIONS
  The different decay kinetics of GABA(A)Rs expressed in amacrine cells of geph(+/+) and of geph(-/-) retinas suggests that these cells express at least two types of GABA(A)R subtypes. In amacrine cells of geph(-/-) mice, a specific GABA(A)R subtype that may contain the alpha2 subunit, is impaired by the absence of gephyrin, whereas other GABA(A)Rs appear to function normally.
authors.affiliation: Department of Neuroanatomy, Max-Planck-Institute for Brain Research, Frankfurt/M, Germany.
authors.forename: Jorge
authors.initials: J
authors.lastname: Pérez-León
authors.forename: Moritz J
authors.initials: MJ
authors.lastname: Frech
authors.forename: Jörn E
authors.initials: JE
authors.lastname: Schröder
authors.forename: Frauke
authors.initials: F
authors.lastname: Fischer
authors.forename: Matthias
authors.initials: M
authors.lastname: Kneussel
authors.forename: Heinz
authors.initials: H
authors.lastname: Wässle
authors.forename: Kurt H
authors.initials: KH
authors.lastname: Backus
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002352:Carrier Proteins; D023902:Chromosome Pairing / Q000502:physiology*; D004594:Electrophysiology; D019706:Excitatory Postsynaptic Potentials; D005260:Female; D019084:Fluorescent Antibody Technique, Indirect; D008297:Male; D008565:Membrane Proteins / Q000172:deficiency; D051379:Mice; D009474:Neurons / Q000502:physiology*; D009924:Organ Culture Techniques; D018408:Patch-Clamp Techniques; D011247:Pregnancy; D011963:Receptors, GABA-A / Q000378:metabolism; D018009:Receptors, Glycine / Q000378:metabolism; D012160:Retina / Q000166:cytology*
chemical_list: D002352:Carrier Proteins; D008565:Membrane Proteins; D011963:Receptors, GABA-A; D018009:Receptors, Glycine; C073441:gephyrin