Details

Autor(en) / Beteiligte

• Bessaih, Thomas
• Bourgeais, Laurence
• Badiu, Carmen I
• Carter, David A
• Toth, Tibor I
• Ruano, Diego
• Lambolez, Bertrand
• Crunelli, Vincenzo
• Leresche, Nathalie

Titel

Nucleus-Specific Abnormalities of GABAergic Synaptic Transmission in a Genetic Model of Absence Seizures

Ist Teil von

• Journal of neurophysiology, 2006-12, Vol.96 (6), p.3074-3081

Ort / Verlag

United States: Am Phys Soc

Erscheinungsjahr

2006

Quelle

MEDLINE

Beschreibungen/Notizen

• 1 Université Pierre et Marie Curie, and Centre National de la Recherche Scientifique, Paris, France; 2 School of Biosciences, Cardiff University, Cardiff, United Kingdom; and 3 Deparmento de Bioquímica, Bromatología, Toxicología y Medicina Legal, Facultad de Farmacia, Sevilla, Spain 4 Submitted 3 July 2006; accepted in final form 7 September 2006 Human and experimental studies indicate that molecular genetic changes in GABA A receptors may underlie the expression of spike-and-waves discharges (SWDs) occurring during absence seizures. However, the full spectrum of the genetic defects underlying these seizures has only been partially elucidated, the expression and functional profiles of putative abnormal protein(s) within the thalamocortical network are undefined, and the pathophysiological mechanism(s) by which these proteins would lead to absence paroxysms are poorly understood. Here we investigated GABA A inhibitory postsynaptic currents (IPSCs) in key thalamocortical areas, i.e., the somatosensory cortex, ventrobasal thalamus (VB) and nucleus reticularis thalami (NRT), in preseizure genetic absence epilepsy rats from Strasbourg (GAERS), a well-established genetic model of typical absence seizures that shows no additional neurological abnormalities, and compared their properties to age-matched non-epileptic controls (NECs). Miniature GABA A IPSCs of VB and cortical layers II/III neurons were similar in GAERS and NEC, whereas in GAERS NRT neurons they had 25% larger amplitude, 40% faster decay. In addition, baclofen was significantly less effective in decreasing the frequency of NRT mIPSCs in GAERS than in NEC, whereas no difference was observed for cortical and VB mIPSCS between the two strains. Paired-pulse depression was 45% smaller in GAERS NRT, but not in VB, and was insensitive to GABA B antagonists. These results point to subtle, nucleus-specific, GABA A receptor abnormalities underlying SWDs of typical absence seizures rather than a full block of these receptors across the whole thalamocortical network, and their occurrence prior to seizure onset suggests that they might be of epileptogenic significance. Address for reprint requests and other correspondence: N. Leresche, Neurobiologie des Processus Adaptatifs, UMR 7102 CNRS, Université Pierre et Marie Curie-Paris 6, 9 quai St Bernard, 75252 Paris Cedex 05, France (E-mail: nathalie.leresche{at}snv.jussieu.fr )