Blockade of AMPA-receptors attenuates 4-aminopyridine seizures, decreases the activation of inhibitory neurons but is ineffective against seizure-related astrocytic swelling

Epilepsy Res. 2008 Jan;78(1):22-32. doi: 10.1016/j.eplepsyres.2007.10.004. Epub 2007 Nov 26.

Abstract

The neurotransmitter glutamate plays a pivotal role in the development of the neuropathological sequelae following acute seizures. Our previous data proved the efficacy of the NMDA-receptor antagonists on the symptoms, survival and neuronal activation in the 4-aminopyridine- (4-AP) induced seizures. In this study, we examined the effects of two different doses of a non-competitive, selective, allosteric AMPA-receptor antagonist, GYKI 52466. GYKI 52466 was effective in prolonging the latency to generalised seizures and reduction of seizure mortality. However, the effects on neuronal c-fos expression and astrocyte swelling were complex. The 25mg/kg dose of GYKI 52466 was effective in reducing the c-fos immunoreactivity (IR) in the hippocampus only. In the neocortex the overall c-fos-IR cell counts were increased significantly. Investigation of the neocortical parvalbumin-containing interneuron population proved that GYKI 52466 decreased c-fos expression. The 50mg/kg dose of GYKI 52466 significantly reduced the c-fos-IR in the neo- and allocortex, not only in principal neurons, but also in the parvalbumin-positive interneurons. The GYKI 52466-pretreatment did not prevent the astrocyte swelling in the investigated cortical areas; thus we conclude that the AMPA-receptors have little if any involvement in the in the mediation of neuropathological alterations in acute convulsions.

MeSH terms

  • 4-Aminopyridine
  • Analysis of Variance
  • Animals
  • Astrocytes / drug effects
  • Astrocytes / pathology*
  • Astrocytes / ultrastructure
  • Behavior, Animal / drug effects
  • Benzodiazepines / pharmacology
  • Brain / drug effects
  • Brain / pathology
  • Disease Models, Animal
  • Dose-Response Relationship, Drug
  • Excitatory Amino Acid Antagonists / pharmacology
  • Gene Expression Regulation / drug effects
  • Male
  • Microscopy, Electron, Transmission
  • Motor Activity / drug effects
  • Neural Inhibition / drug effects
  • Neural Inhibition / physiology*
  • Parvalbumins / metabolism
  • Proto-Oncogene Proteins c-fos / metabolism
  • Rats
  • Rats, Wistar
  • Receptors, AMPA / metabolism*
  • Seizures / chemically induced
  • Seizures / drug therapy
  • Seizures / metabolism*
  • Seizures / physiopathology

Substances

  • Excitatory Amino Acid Antagonists
  • Parvalbumins
  • Proto-Oncogene Proteins c-fos
  • Receptors, AMPA
  • GYKI 52466
  • Benzodiazepines
  • 4-Aminopyridine