Reduction of vesicle-associated membrane protein 2 expression leads to a kindling-resistant phenotype in a murine model of epilepsy

Neuroscience. 2012 Jan 27;202:77-86. doi: 10.1016/j.neuroscience.2011.11.055. Epub 2011 Dec 13.

Abstract

Our previous work has correlated permanent alterations in the rat neurosecretory machinery with epileptogenesis. Such findings highlighted the need for a greater understanding of the molecular mechanisms underlying epilepsy so that novel therapeutic regimens can be designed. To this end, we examined kindling in transgenic mice with a defined reduction of a key element of the neurosecretory machinery: the v-SNARE (vesicle-bound SNAP [soluble NSF attachment protein] receptor), synaptobrevin/vesicle-associated membrane protein 2 (VAMP2). Initial analysis of biochemical markers, which previously displayed kindling-dependent alterations in rat hippocampal synaptosomes, showed similar trends in both wild-type and VAMP2(+/-) mice, demonstrating that kindled rat and mouse models are comparable. This report focuses on the effects that a ~50% reduction of synaptosomal VAMP2 has on the progression of electrical kindling and on glutamate release in hippocampal subregions. Our studies show that epileptogenesis is dramatically attenuated in VAMP2(+/-) mice, requiring both higher current and more stimulations to reach a fully kindled state (two successive Racine stage 5 seizures). Progression through the five identifiable Racine stages was slower and more variable in the VAMP2(+/-) animals compared with the almost linear progression seen in wild-type littermates. Consistent with the expected effects of reducing a major neuronal v-SNARE, glutamate-selective, microelectrode array (MEA) measurements in specific hippocampal subregions of VAMP2(+/-) mice showed significant reductions in potassium-evoked glutamate release. Taken together these studies demonstrate that manipulating the levels of the neurosecretory machinery not only affects neurotransmitter release but also mitigates kindling-induced epileptogenesis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • CA1 Region, Hippocampal / drug effects
  • CA1 Region, Hippocampal / metabolism
  • CA2 Region, Hippocampal / drug effects
  • CA2 Region, Hippocampal / metabolism
  • Data Interpretation, Statistical
  • Dentate Gyrus / drug effects
  • Dentate Gyrus / metabolism
  • Electric Stimulation
  • Epilepsy / physiopathology*
  • Glutamic Acid / metabolism
  • Kindling, Neurologic / genetics*
  • Kindling, Neurologic / physiology*
  • Mice
  • Mice, Inbred C57BL
  • Mice, Knockout
  • Microelectrodes
  • SNARE Proteins / physiology
  • Vesicle-Associated Membrane Protein 2 / biosynthesis*
  • Vesicle-Associated Membrane Protein 2 / genetics
  • Vesicle-Associated Membrane Protein 2 / physiology*

Substances

  • SNARE Proteins
  • Vesicle-Associated Membrane Protein 2
  • vesicle-associated membrane protein 2, mouse
  • Glutamic Acid