Neurochemical Research

, Volume 28, Issue 11, pp 1649–1658

The Recurrent Mossy Fiber Pathway of the Epileptic Brain

  • J. Victor Nadler
Article

DOI: 10.1023/A:1026004904199

Cite this article as:
Nadler, J.V. Neurochem Res (2003) 28: 1649. doi:10.1023/A:1026004904199

Abstract

The dentate gyrus is believed to play a key role in the pathogenesis of temporal lobe epilepsy. In normal brain the dentate granule cells serve as a high-resistance gate or filter, inhibiting the propagation of seizures from the entorhinal cortex to the hippocampus. The filtering function of the dentate gyrus depends in part on the near absence of monosynaptic connections among granule cells. In humans with temporal lobe epilepsy and in animal models of temporal lobe epilepsy, dentate granule cells form an interconnected synaptic network associated with loss of hilar interneurons. This recurrent mossy fiber pathway mediates reverberating excitation that can reduce the threshold for granule cell synchronization. Factors that augment activity in this pathway include modest increases in [K+]o; loss of GABA inhibition; short-term, frequency-dependent facilitation (frequencies of 1–2 Hz); feedback activation of kainate autoreceptors; and release of zinc from recurrent mossy fiber boutons. Factors that diminish activity include short-term, frequency-dependent depression (frequencies <1 Hz); feedback activation of type II metabotropic glutamate receptors; and the potential release of GABA, neuropeptide Y, adenosine, and dynorphin from recurrent mossy fiber boutons. The axon sprouting and reactive synaptogenesis that follow seizure-related brain damage can also create or strengthen recurrent excitation in other brain regions. These changes are expected to facilitate participation of these regions in seizures. Thus, reactive processes that are often considered important for recovery of function after most brain injuries probably contribute to neurological dysfunction in epilepsy.

Epilepsymossy fiberhippocampusaxon sproutingglutamatedentate granule cell

Copyright information

© Plenum Publishing Corporation 2003

Authors and Affiliations

  • J. Victor Nadler
    • 1
  1. 1.Department of Pharmacology and Cancer Biology and Department of NeurobiologyDuke University Medical CenterDurham