| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Journal of Neurophysiology, Vol 75, Issue 5 1901-1908, Copyright © 1996 by APS
ARTICLES |
M. Isokawa
Brain Research Institute, University of California, Los Angeles, 90024-1761, USA.
1. Inhibitory postsynaptic currents (IPSCs) were studied in hippocampal dentate granule cells (DGCs) in the pilocarpine model and human temporal lobe epilepsy, with the use of the whole cell patch-clamp recording technique in slice preparations. 2. In the pilocarpine model, hippocampal slices were prepared from rats that were allowed to experience spontaneous seizures for 2 mo. Human hippocampal specimens were obtained from epileptic patients who underwent surgical treatment for medically intractable seizures. 3. IPSCs were generated by single perforant path stimulation and recorded at a membrane potential (Vm) of 0 mV near the reversal potential of glutamate excitatory postsynaptic currents in the voltage-clamp recording. IPSCs were pharmacologically identified as gamma-aminobutyric acid-A (GABAA) IPSCs by 10 microM bicuculline methiodide. 4. During low-frequency stimulation, IPSCs were not different in amplitude among non-seizure-experienced rat hippocampi, human nonsclerotic hippocampi, seizure-experienced rat hippocampi, and human sclerotic hippocampi. In the last two groups of DGCs, current-clamp recordings indicated the presence of prolonged excitatory postsynaptic potentials (EPSPs) mediated by the N-methyl-D-aspartate (NMDA) receptor. 5. High-frequency stimulation, administered at Vm = -30 mV to activate NMDA currents, reduced GABAA IPSC amplitude specifically in seizure-experienced rat hippocampi (t = 2.5, P < 0.03) and human sclerotic hippocampi (t = 7.7, P < 0.01). This reduction was blocked by an NMDA receptor antagonist, 2-amino-5-phosphonovaleric acid (APV) (50 microM). The time for GABAA IPSCs to recover to their original amplitude was also shortened by the application of APV. 6. I conclude that, when intensively activated, NMDA receptor-mediated excitatory transmission may interact with GABAergic synaptic inhibition in DGCs in seizure-experienced hippocampus to transiently reduce GABA(A) receptor-channel function. Such interactions may contribute to give rise to epileptic excitation in chronically seizure-prone hippocampus.
This article has been cited by other articles:
|
|
 |
|
  H.-J. Feng, G. C. Mathews, C. Kao, and R. L. Macdonald Alterations of GABAA-Receptor Function and Allosteric Modulation During Development of Status Epilepticus J Neurophysiol, March 1, 2008; 99(3): 1285 - 1293. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
K. M. Jacobs and D. A. Prince Excitatory and Inhibitory Postsynaptic Currents in a Rat Model of Epileptogenic Microgyria J Neurophysiol, February 1, 2005; 93(2): 687 - 696. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 M. Kobayashi and P. S. Buckmaster Reduced Inhibition of Dentate Granule Cells in a Model of Temporal Lobe Epilepsy J. Neurosci., March 15, 2003; 23(6): 2440 - 2452. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. Doherty and R. Dingledine Reduced Excitatory Drive onto Interneurons in the Dentate Gyrus after Status Epilepticus J. Neurosci., March 15, 2001; 21(6): 2048 - 2057. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Lynch, U. Sayin, G. Golarai, and T. Sutula NMDA Receptor-Dependent Plasticity of Granule Cell Spiking in the Dentate Gyrus of Normal and Epileptic Rats J Neurophysiol, December 1, 2000; 84(6): 2868 - 2879. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. L. Hardison, M. M. Okazaki, and J. V. Nadler Modest Increase in Extracellular Potassium Unmasks Effect of Recurrent Mossy Fiber Growth J Neurophysiol, November 1, 2000; 84(5): 2380 - 2389. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
H. E. Scharfman, J. H. Goodman, and A. L. Sollas Granule-Like Neurons at the Hilar/CA3 Border after Status Epilepticus and Their Synchrony with Area CA3 Pyramidal Cells: Functional Implications of Seizure-Induced Neurogenesis J. Neurosci., August 15, 2000; 20(16): 6144 - 6158. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Loup, H.-G. Wieser, Y. Yonekawa, A. Aguzzi, and J.-M. Fritschy Selective Alterations in GABAA Receptor Subtypes in Human Temporal Lobe Epilepsy J. Neurosci., July 15, 2000; 20(14): 5401 - 5419. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Alkondon, E. F. R. Pereira, H. M. Eisenberg, and E. X. Albuquerque Nicotinic Receptor Activation in Human Cerebral Cortical Interneurons: a Mechanism for Inhibition and Disinhibition of Neuronal Networks J. Neurosci., January 1, 2000; 20(1): 66 - 75. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. PENSCHUCK, J. PAYSAN, O. GIORGETTA, and J.-M. FRITSCHY Activity-Dependent Regulation of GABAA Receptors Ann. N.Y. Acad. Sci., April 30, 1999; 868(1): 654 - 666. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. M. Okazaki, P. Molnar, and J. V. Nadler Recurrent Mossy Fiber Pathway in Rat Dentate Gyrus: Synaptic Currents Evoked in Presence and Absence of Seizure-Induced Growth J Neurophysiol, April 1, 1999; 81(4): 1645 - 1660. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Morin, C. Beaulieu, and J.-C. Lacaille Cell-Specific Alterations in Synaptic Properties of Hippocampal CA1 Interneurons After Kainate Treatment J Neurophysiol, December 1, 1998; 80(6): 2836 - 2847. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
M. Isokawa, M. Levesque, I. Fried, and J. Engel Jr. Glutamate Currents in Morphologically Identified Human Dentate Granule Cells in Temporal Lobe Epilepsy J Neurophysiol, June 1, 1997; 77(6): 3355 - 3369. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
