Abstract:

AIM: Dysmorphic neurons and balloon cells in focal cortical dysplasia (FCD) reportedly show immaturity and abnormal differentiation with neuronal and glial components. Although normal-looking neurons (NL-neurons) in FCD are major constituent elements, their biological characteristics have never been identified. The aim of this study was to investigate maturation of NL-neurons with the focus on neuronal developmental lineage.
METHODS: Eighteen FCD surgical specimens and controls were examined immunohistochemically using the antibodies for nestin, mammalian achaete-scute complex homolog 1 (Mash1), prospero-related homeobox 1 (Prox1), neuron-specific beta-III tubulin (Tuj1) and microtubule-associated protein 2 (MAP2) of neuronal lineage, glutamic acid decarboxylase (GAD), calretinin (CR) and calbindin (CB) of interneuron markers, and glial fibrillary-acidic protein (GFAP) of glial cell marker. Additionally, we performed fluorescent-double staining with these markers, and semi-quantitative analysis.
RESULTS: NL-neurons in FCD had both mature and immature components, without interneuron components. NL-neurons in FCD showed abnormal maturation with the combined expression of MAP2 and Mash1/Prox1. Prox1-containing cell distribution in the deep layer was different from that of Mash1-containing cells in the superficial area. The MAP2-containing cell concentration decreased in the order of type I-A, I-B, II-A and II-B, but the Tuj1-containing cell concentration increased.
CONCLUSION: These findings may reflect differences in neuronal function and expression timing in developmental stages. From the standpoint of molecular expression, abnormal maturation of NL-neurons may initiate synaptic dysfunction, resulting in intractable seizures of FCD.

日本語要旨:

局在性大脳皮質異形成(FCD)は小児の難治性てんかんで、病理学的に異型神経細胞や巨大細胞があることを特徴とする。治療的切除された標本を用いて、神経細胞に発生学的異常がないかについて免疫組織学的に検討した結果、一見正常な神経細胞でも発生・分化異常があることを突き止めた。