Contributions of mossy fiber and CA1 pyramidal cell sprouting to dentate granule cell hyperexcitability in kainic acid-treated hippocampal slice cultures.

Published

Journal Article

Axonal sprouting like that of the mossy fibers is commonly associated with temporal lobe epilepsy, but its significance remains uncertain. To investigate the functional consequences of sprouting of mossy fibers and alternative pathways, kainic acid (KA) was used to induce robust mossy fiber sprouting in hippocampal slice cultures. Physiological comparisons documented many similarities in granule cell responses between KA- and vehicle-treated cultures, including: seizures, epileptiform bursts, and spontaneous excitatory postsynaptic currents (sEPSCs) >600 pA. GABAergic control and contribution of glutamatergic synaptic transmission were similar. Analyses of neurobiotin-filled CA1 pyramidal cells revealed robust axonal sprouting in both vehicle- and KA-treated cultures, which was significantly greater in KA-treated cultures. Hilar stimulation evoked an antidromic population spike followed by variable numbers of postsynaptic potentials (PSPs) and population spikes in both vehicle- and KA-treated cultures. Despite robust mossy fiber sprouting, knife cuts separating CA1 from dentate gyrus virtually abolished EPSPs evoked by hilar stimulation in KA-treated but not vehicle-treated cultures, suggesting a pivotal role of functional afferents from CA1 to dentate gyrus in KA-treated cultures. Together, these findings demonstrate striking hyperexcitability of dentate granule cells in long-term hippocampal slice cultures after treatment with either vehicle or KA. The contribution to hilar-evoked hyperexcitability of granule cells by the unexpected axonal projection from CA1 to dentate in KA-treated cultures reinforces the idea that axonal sprouting may contribute to pathologic hyperexcitability of granule cells.

Full Text

Duke Authors

Cited Authors

  • Bausch, SB; McNamara, JO

Published Date

  • December 2004

Published In

Volume / Issue

  • 92 / 6

Start / End Page

  • 3582 - 3595

PubMed ID

  • 15269228

Pubmed Central ID

  • 15269228

International Standard Serial Number (ISSN)

  • 0022-3077

Digital Object Identifier (DOI)

  • 10.1152/jn.01028.2003

Language

  • eng

Conference Location

  • United States