Granule cell dispersion is not accompanied by enhanced neurogenesis in temporal lobe epilepsy patients.
Granule cell dispersion (GCD) in the dentate gyrus is a frequent feature of Ammon's horn sclerosis (AHS) which is often associated with temporal lobe epilepsy (TLE). It has been hypothesized that GCD may be caused by an abnormal migration of newly born granule cells. To test this hypothesis, we used markers of proliferation and neurogenesis and immunocytochemical methods as well as quantitative Western blot and real-time RT-PCR analyses in surgically resected hippocampi from TLE patients and controls. Below the age of 1 year, Ki-67-immunopositive nuclei were detected in the subgranular zone of the dentate gyrus, but not in the dentate of TLE patients independent of age. The expression of the proliferation marker minichromosome maintenance protein 2 (mcm2) and of doublecortin (DCX) decreased significantly with age in controls and in TLE patients, but the expression of both proteins was independent of the degree of AHS and GCD. Quantitative real-time RT-PCR confirmed these findings at the level of gene expression. In contrast, immunocytochemistry for glial fibrillary acidic protein (GFAP) and vimentin as well as Golgi staining revealed a radially aligned glial network in the region of GCD. GFAP-positive fiber length significantly increased with the severity of GCD. These results indicate that epileptic activity does not stimulate neurogenesis in the human dentate gyrus and that GCD probably does not result from a malpositioning of newly generated granule cells, but rather from an abnormal migration of mature granule cells along a radial glial scaffold.
Fahrner
Alexander
A
Experimental Epilepsy Group, Neurocenter, University of Freiburg, Breisacher Strasse 64, D-79106 Freiburg, Germany.
Kann
Gunda
G
Flubacher
Armin
A
Heinrich
Christophe
C
Freiman
Thomas M
TM
Zentner
Josef
J
Frotscher
Michael
M
Haas
Carola A
CA
D000293:Adolescent; D000328:Adult; D015153:Blotting, Western; D001932:Brain Neoplasms / Q000473:pathology; D002467:Cell Nucleus / Q000378:metabolism; D002648:Child; D003594:Cytoplasmic Granules / Q000473:pathology*; D018891:Dentate Gyrus / Q000254:growth & development / Q000473:pathology; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D004833:Epilepsy, Temporal Lobe / Q000473:pathology*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005909:Glioblastoma / Q000473:pathology; D006624:Hippocampus / Q000254:growth & development / Q000473:pathology*; D006801:Humans; D007150:Immunohistochemistry; D007223:Infant; D019394:Ki-67 Antigen / Q000276:immunology; D008297:Male; D008869:Microtubule-Associated Proteins / Q000096:biosynthesis; D008875:Middle Aged; D008938:Mitosis / Q000502:physiology; D009457:Neuroglia / Q000502:physiology; D009474:Neurons / Q000502:physiology; D009479:Neuropeptides / Q000096:biosynthesis; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014746:Vimentin / Q000378:metabolism
C000714328:DCX protein, human; D000089622:Doublecortin Domain Proteins; D000089662:Doublecortin Protein; D005904:Glial Fibrillary Acidic Protein; D019394:Ki-67 Antigen; D008869:Microtubule-Associated Proteins; D009479:Neuropeptides; D014746:Vimentin