Artikel
Reappearance of radial glial cells in the dentate gyrus of the hippocampus in patients with temporal lobe epilepsy correlates with the degree of granule cell dispersion
Wiederauftreten von Radialgliazellen im Gyrus dentatus von Patienten mit Temporallappenepilepsie korreliert mit dem Ausmaß der Körnerzelldispersion
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Autoren
Veröffentlicht: | 4. Mai 2005 |
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Gliederung
Text
Objective
Granule cell dispersion (GCD) in the dentate gyrus is a characteristic feature of Ammon's horn sclerosis (AHS) which often accompanies temporal lobe epilepsy (TLE) in humans. Little is known about the molecular mechanisms underlying the development of GCD. One hypothesis postulates a local migration defect during hippocampal development which is supported by a local reelin deficiency associated with GCD in hippocampi of TLE patients. Since radial glial cells provide a scaffold for migrating neurons during development, the occurrence of radial glial cells was investigated.
Methods
Hippocampal specimens of TLE patients with AHS were processed for immunocytochemistry and Golgi-Silver-Impregnation.
Results
Immunocytochemistry for glial fibrillary acidic protein (GFAP) revealed a dense, radially aligned network of GFAP-immunopositive fibres in the granule cell layer of epileptic patients, but not in control hippocampi. The length of stained fibres was determined and the width of the granule cell layer (GCL) was measured in adjacent Nissl-stained sections of human hippocampi obtained by neurosurgery (n=10) and by autopsy (n=5). We found that the degree of granule cell dispersion was directly correlated to an increased length of radial glial fibres. In controls and in hippocampi from patients with mild GCD, GFAP-positive radial glial cells displayed short and less developed fibres. In addition, similar results were obtained by Golgi-impregnation: in control hippocampi only normal astrocytes were found, whereas in TLE specimen astrocytes were visualised which displayed long, radial processes in the area of dispersion.
Conclusions
These results suggest that granule cells in the dentate gyrus of TLE patients may use radial glial cells as guiding structures for migration, thereby contributing to the pathology of granule cell dispersion.