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Epileptogenicity Correlated with Increased N ‐Methyl‐ d ‐Aspartate Receptor Subunit NR2A/B in Human Focal Cortical Dysplasia
Author(s) -
Najm Imad M.,
Ying Zhong,
Babb Thomas,
Mohamed Armin,
Hadam Jennifer,
LaPresto Eric,
Wyllie Elaine,
Kotagal Prakash,
Bingaman William,
Foldvary Nancy,
Morris Harold,
Lüders Hans O.
Publication year - 2000
Publication title -
epilepsia
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.687
H-Index - 191
eISSN - 1528-1167
pISSN - 0013-9580
DOI - 10.1111/j.1528-1157.2000.tb00281.x
Subject(s) - cortical dysplasia , nmda receptor , glutamate receptor , epileptogenesis , epilepsy , biology , protein subunit , pathology , receptor , dendritic spine , ifenprodil , neuroscience , hippocampal formation , medicine , biochemistry , gene
Summary:Purpose : Human cortical dysplasia (CD) is a frequent cause of medically intractable focal epilepsy. The neurotransmitter mechanisms of epileptogenicity in these lesions have been attributed to changes in various glutamate receptor subtypes. Increased N ‐methyl‐ d ‐aspartate (NMDA) receptor (NR) 2A/B coassembled with NRI subunits has been shown in focal epileptic CD. The purpose of this study is to correlate in situ CD epileptogenicity and the expression of various glutamate receptor subtypes. Methods : The histopathological, morphological, and immu‐nocytochemical findings in cortical tissue resected from five patients with medically intractable epilepsy and CD were correlated with electroencephalographic data recorded from sub‐dural grids. The NMDA antibodies identified subunits NRI (splicing variants la, lb, 2a, and 2b) and NR2A/B. Results : Epileptogenic specimens displayed the following common features: (a) widespread histological abnormalities of horizontal and columnar dyslamination, neurons with inverted polarity, and more extensive dendritic changes; (b) significantly higher NR2A/B immunoreactivity in both the dysplastic somata and all their dendritic processes; and (c) no statistically significant change in NR1 subunit expression but a more pronounced staining of the apical dendrites in highly epileptogenic cortex. These abnormalities were either absent or minimal in resected specimens that did not show evidence of severe in vivo epileptogenicity. Conclusion : These studies provide direct evidence for a major contribution of the NR2A/B subunit in CD‐induced epileptogenicity.