Original Research Article
Upregulated H-Current in hyperexcitable CA1 dendrites after febrile seizures
Department of Anatomy & Neurobiology, University of California, USA
Somatic recordings from CA1 pyramidal cells indicated a persistent upregulation of the h-current (Ih) after experimental febrile seizures. Here, we examined febrile seizure-induced long-term changes in Ih and neuronal excitability in CA1 dendrites. Cell-attached recordings showed that dendritic Ih was significantly upregulated, with a depolarized half-activation potential and increased maximal current. Although enhanced Ih is typically thought to be associated with decreased dendritic excitability, whole-cell dendritic recordings revealed a robust increase in action potential firing after febrile seizures. We turned to computational simulations to understand how the experimentally observed changes in Ih influence dendritic excitability. Unexpectedly, the simulations, performed in three previously published CA1 pyramidal cell models, showed that the experimentally observed increases in Ih resulted in a general enhancement of dendritic excitability, primarily due to the increased Ih-induced depolarization of the resting membrane potential overcoming the excitability-depressing effects of decreased dendritic input resistance. Taken together, these experimental and modeling results reveal that, contrary to the exclusively anti-convulsive role often attributed to increased Ih in epilepsy, the enhanced Ih can co-exist with, and possibly even contribute to, persistent dendritic hyperexcitability following febrile seizures in the developing hippocampus.
Keywords: epilepsy, h-current, dendrite
Copyright: © 2008 Dyhrfjeld-Johnsen, Morgan, Földy and Soltesz. This is an open-access article subject to an exclusive license agreement between the authors and the Frontiers Research Foundation, which permits unrestricted use, distribution, and reproduction in any medium, provided the original authors and source are credited.
*Correspondence: Robert J. Morgan, Department of Anatomy, University of California, 193 Irvine Hall, Irvine, CA 92697 Phone: (949) 824-3967. e-mail: rjmorgan@uci.edu
Citation: Dyhrfjeld-Johnsen J, Morgan RJ, Földy C and Soltesz I (2008) Upregulated H-Current in hyperexcitable CA1 dendrites after febrile seizures. Front. Cell. Neurosci. (2008) 2:2. doi:10.3389/neuro.03.002.2008
Received: 14 February 2008; paper pending published: 12 March 2008; accepted: 01 April 2008; published online: 17 April 2008.
Edited by:
Stephen R. Williams, University of Cambridge, UK
Reviewed by:
Matthew Nolan, The University of Edinburgh, UK
Mala Shah, University of London, UK
Mala Shah, University of London, UK
*Correspondence: Robert J. Morgan, Department of Anatomy, University of California, 193 Irvine Hall, Irvine, CA 92697 Phone: (949) 824-3967. e-mail: rjmorgan@uci.edu


