Postnatal Development of a New Type of Epileptiform Activity in the Rat Hippocampus.
From: Institute of Physiology and Biophysics, Department of Physiology, University of Aarhus, Denmark.
Brain research
- Publish Date: Jun 2006
- ISSN: 0006-8993
- Volume: 1096
- Issue: 1
- Pages: 61-9
- Medium: Print
- Language: English
- Citation (JAMA): Skov Jane, Andreasen Mogens, Nedergaard Steen, et al. Postnatal Development of a New Type of Epileptiform Activity in the Rat Hippocampus.. Brain Res. Jun 2006;1096:61-9
Abstract
Long-term application of Cs(+) (5 mM) induces an epileptiform field potential (Cs-FP) in area CA1 of the rat hippocampus, which is independent of N-methyl-D-aspartate (NMDA) and non-NMDA glutamate receptors and gamma-aminobutyric acid (GABA)(A) receptors. To gain insight into possible mechanisms for the induction of the Cs-FP, we investigated the postnatal development of the response. In brain slices prepared from rats at different ages, the Cs-FP was evoked by stimulation of the Schaffer-collateral-commisural pathway. We found that expression of this potential was clearly dependent on the postnatal age. Thus, the Cs-FP was completely absent at 1 week of age. By 2 weeks, a reduced form of the response was observed, whereas slices taken from 3-week-old rats, displayed full Cs-FP, which were indistinguishable in size and shape from the adult form. In the presence of 4-aminopyridine, potentials resembling the Cs-FP were evoked. These potentials showed a similar age-dependency as the Cs-FP. The Na(+)/K(+) pump inhibitor dihydroouabain (DHO), when present during wash-in of Cs(+), gave a partial block of the Cs-FP in adult slices. This effect was not seen when DHO was applied after development of the Cs-FP. The data indicate that the processes necessary for expression of the Cs-PF are absent at birth and develop during the second postnatal week. We propose that the Cs-FP depends on Cs(+) entry into presynaptic neurons, and that the Na(+)/K(+) pump contributes to this transport of Cs(+). The observed age-dependency could therefore, in part, reflect the delayed development of the Na(+)/K(+) pump.
Mesh Headings (Keywords): 2-Amino-5-phosphonovalerate, 4-Aminopyridine, 6-Cyano-7-nitroquinoxaline-2,3-dione, Aging, Animals, Cesium, Electrophysiology, Epilepsy, Excitatory Amino Acid Antagonists, Excitatory Postsynaptic Potentials, Extracellular Space, GABA Antagonists, Hippocampus, Male, Membrane Potentials, Patch-Clamp Techniques, Potassium Channel Blockers, Rats, Rats, Wistar, Receptors, Glutamate, Sodium-Potassium-Exchanging ATPase
Check for Full Text / PubMed Unique Identifier (PMID): 16725129
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