Molecular and functional changes in voltage-dependent Na(+) channels following pilocarpine-induced status epilepticus in rat dentate granule cells

Neuroscience. 2003;119(2):323-33. doi: 10.1016/s0306-4522(03)00168-4.


Status epilepticus (S.E.) is known to lead to a large number of changes in the expression of voltage-dependent ion channels and neurotransmitter receptors. In the present study, we examined whether an episode of S.E. induced by pilocarpine in vivo alters functional properties and expression of voltage-gated Na(+) channels in dentate granule cells (DGCs) of the rat hippocampus. Using patch-clamp recordings in isolated DGCs, we show that the voltage-dependent inactivation curve is significantly shifted toward depolarizing potentials following S.E. (half-maximal inactivation at -43.2+/-0.6 mV) when compared with control rats (-48.2+/-0.8 mV, P<0.0001). The voltage-dependent activation curve is significantly shifted to more negative potentials following S.E., with half-maximal activation at -28.6+/-0.8 mV compared with -25.8+/-0.9 mV in control animals (P<0.05). The changes in voltage dependence resulted in an augmented window current due to increased overlap between the activation and inactivation curve. In contrast to Na(+) channel voltage-dependence, S.E. caused no changes in the kinetics of fast or slow recovery from inactivation. The functional changes were accompanied by altered expression of Na(+) channel subunits measured by real-time reverse transcription-polymerase chain reaction in dentate gyrus microslices. We investigated expression of the pore-forming alpha subunits Na(v)1.1-Na(v)1.3 and Na(v)1.5-Na(v)1.6, in addition to the accessory subunits beta(1) and beta(2). The Na(v)1.2 and Na(v)1.6 subunit as well as the beta(1) subunit were persistently down-regulated up to 30 days following S.E. The beta(2) subunit was transiently down-regulated on the first and third day following S.E. These results indicate that differential changes in Na(+) channel subunit expression occur in concert with functional changes. Because coexpression of beta subunits is known to robustly shift the voltage dependence of inactivation in a hyperpolarizing direction, we speculate that a down-regulation of beta-subunit expression may contribute to the depolarizing shift in the inactivation curve following S.E.

Publication types

  • Comparative Study
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Dentate Gyrus / metabolism*
  • Electric Conductivity
  • Electric Stimulation
  • Fluorescent Dyes / pharmacokinetics
  • Gene Expression Regulation / drug effects
  • In Vitro Techniques
  • Male
  • Matched-Pair Analysis
  • Membrane Potentials
  • Muscarinic Agonists
  • Neurons / physiology
  • Patch-Clamp Techniques / methods
  • Pilocarpine*
  • Protein Subunits / chemistry
  • Protein Subunits / genetics
  • RNA, Messenger / biosynthesis
  • Rats
  • Rats, Wistar
  • Reverse Transcriptase Polymerase Chain Reaction / methods
  • Rhodamines / pharmacokinetics
  • Sodium Channels / genetics
  • Sodium Channels / physiology*
  • Status Epilepticus / chemically induced
  • Status Epilepticus / pathology*
  • Synaptophysin / chemistry
  • Synaptophysin / genetics
  • Time Factors


  • 5-carboxytetramethylrhodamine succinimidyl ester
  • Fluorescent Dyes
  • Muscarinic Agonists
  • Protein Subunits
  • RNA, Messenger
  • Rhodamines
  • Sodium Channels
  • Synaptophysin
  • Pilocarpine