Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats
We investigated the potential of 4-AP (50–100 μM) to induce seizure-like events (SLEs) in combined entorhinal cortex–hippocampal slices from Sprague Dawley rats which developed spontaneous limbic seizures following kainic acid induced status epilepticus. Slices from control rats (n=8) displayed SLEs...
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Elsevier
2008-02-01
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| Series: | Neurobiology of Disease |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S0969996107001970 |
| _version_ | 1818735008397918208 |
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| author | Robert K. Zahn Else A. Tolner Christian Derst Clemens Gruber Rüdiger W. Veh Uwe Heinemann |
| author_facet | Robert K. Zahn Else A. Tolner Christian Derst Clemens Gruber Rüdiger W. Veh Uwe Heinemann |
| author_sort | Robert K. Zahn |
| collection | DOAJ |
| description | We investigated the potential of 4-AP (50–100 μM) to induce seizure-like events (SLEs) in combined entorhinal cortex–hippocampal slices from Sprague Dawley rats which developed spontaneous limbic seizures following kainic acid induced status epilepticus. Slices from control rats (n=8) displayed SLEs in the entorhinal and perirhinal cortex upon application of 50 or 100 μM 4-AP. By contrast, 4-AP failed to induce SLEs in slices from chronic epileptic rats (n=13) except for one slice from one rat. This animal displayed only minor cell loss in layer III of the entorhinal cortex, in contrast to the other epileptic rats for which layer III neuronal loss was extensive. In all slices from epileptic rats, 4-AP induced recurrent epileptiform discharges similar to the interictal activity observed in control rats. Combined application of 4-AP (100 μM) and bicuculline methiodide (30 μM) induced frequent and prolonged recurrent epileptiform discharges in both control and chronic epileptic rats. 4-AP at 50–100 μM likely affects potassium channels containing Kv1.4, Kv1.5, Kv3.1 or Kv3.2 subunits. Real-time PCR revealed no significant downregulation of Kv1.4, Kv1.5, Kv3.1 or Kv3.2 in the subiculum, entorhinal and perirhinal cortex from chronic epileptic rats compared to controls. However, the expression of Kv3.4, responding to 4-AP in mM range, was significantly reduced. Using sub-unit-specific antibodies, the real-time PCR findings were confirmed by immunocytochemistry. We suggest that after chronic epilepsy, reorganization in the entorhinal cortex is accompanied by adaptations in homeostatic plasticity with anticonvulsant consequences. |
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| institution | Directory Open Access Journal |
| issn | 1095-953X |
| language | English |
| last_indexed | 2024-12-18T00:14:25Z |
| publishDate | 2008-02-01 |
| publisher | Elsevier |
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| series | Neurobiology of Disease |
| spelling | doaj.art-cc00e529564344c88da24c974c4d0d3d2022-12-21T21:27:33ZengElsevierNeurobiology of Disease1095-953X2008-02-01292186200Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic ratsRobert K. Zahn0Else A. Tolner1Christian Derst2Clemens Gruber3Rüdiger W. Veh4Uwe Heinemann5Institute of Neurophysiology, Charité Universitätsmedizin Berlin, Humboldt Universität, Tucholskystr. 2, D-10117 Berlin, GermanyInstitute of Neurophysiology, Charité Universitätsmedizin Berlin, Humboldt Universität, Tucholskystr. 2, D-10117 Berlin, GermanyInstitute for Integrative Neuroanatomy, Charité Universitätsmedizin Berlin, Humboldt Universität, Philippstr. 12, D-10115 Berlin, GermanyInstitute for Integrative Neuroanatomy, Charité Universitätsmedizin Berlin, Humboldt Universität, Philippstr. 12, D-10115 Berlin, GermanyInstitute for Integrative Neuroanatomy, Charité Universitätsmedizin Berlin, Humboldt Universität, Philippstr. 12, D-10115 Berlin, GermanyInstitute of Neurophysiology, Charité Universitätsmedizin Berlin, Humboldt Universität, Tucholskystr. 2, D-10117 Berlin, Germany; Corresponding author.We investigated the potential of 4-AP (50–100 μM) to induce seizure-like events (SLEs) in combined entorhinal cortex–hippocampal slices from Sprague Dawley rats which developed spontaneous limbic seizures following kainic acid induced status epilepticus. Slices from control rats (n=8) displayed SLEs in the entorhinal and perirhinal cortex upon application of 50 or 100 μM 4-AP. By contrast, 4-AP failed to induce SLEs in slices from chronic epileptic rats (n=13) except for one slice from one rat. This animal displayed only minor cell loss in layer III of the entorhinal cortex, in contrast to the other epileptic rats for which layer III neuronal loss was extensive. In all slices from epileptic rats, 4-AP induced recurrent epileptiform discharges similar to the interictal activity observed in control rats. Combined application of 4-AP (100 μM) and bicuculline methiodide (30 μM) induced frequent and prolonged recurrent epileptiform discharges in both control and chronic epileptic rats. 4-AP at 50–100 μM likely affects potassium channels containing Kv1.4, Kv1.5, Kv3.1 or Kv3.2 subunits. Real-time PCR revealed no significant downregulation of Kv1.4, Kv1.5, Kv3.1 or Kv3.2 in the subiculum, entorhinal and perirhinal cortex from chronic epileptic rats compared to controls. However, the expression of Kv3.4, responding to 4-AP in mM range, was significantly reduced. Using sub-unit-specific antibodies, the real-time PCR findings were confirmed by immunocytochemistry. We suggest that after chronic epilepsy, reorganization in the entorhinal cortex is accompanied by adaptations in homeostatic plasticity with anticonvulsant consequences.http://www.sciencedirect.com/science/article/pii/S0969996107001970Limbic epilepsy4-aminopyridineVoltage-gated potassium channelsSeizure susceptibility |
| spellingShingle | Robert K. Zahn Else A. Tolner Christian Derst Clemens Gruber Rüdiger W. Veh Uwe Heinemann Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats Neurobiology of Disease Limbic epilepsy 4-aminopyridine Voltage-gated potassium channels Seizure susceptibility |
| title | Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats |
| title_full | Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats |
| title_fullStr | Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats |
| title_full_unstemmed | Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats |
| title_short | Reduced ictogenic potential of 4-aminopyridine in the perirhinal and entorhinal cortex of kainate-treated chronic epileptic rats |
| title_sort | reduced ictogenic potential of 4 aminopyridine in the perirhinal and entorhinal cortex of kainate treated chronic epileptic rats |
| topic | Limbic epilepsy 4-aminopyridine Voltage-gated potassium channels Seizure susceptibility |
| url | http://www.sciencedirect.com/science/article/pii/S0969996107001970 |
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