Crino P B, Duhaime A C, Baltuch G, White R
Department of Neurology, University of Pennsylvania School of Medicine, Philadelphia 19104, USA.
Neurology. 2001 Apr 10;56(7):906-13. doi: 10.1212/wnl.56.7.906.
Focal cortical dysplasia is characterized by disorganized cortical lamination, dysplastic and heterotopic neurons, and an association with epilepsy. The contribution that dysplastic and heterotopic neurons make to epileptogenesis in focal cortical dysplasia is unknown and the phenotype of these cells may be distinct. The authors hypothesized that the expression of genes encoding glutamatergic (glutamate [GluR] and N-methyl-D-aspartate NMDA receptors [NR]) and gamma-aminobutyric acid A receptor (GABA(A)R) subunits is distinct in dysplastic and heterotopic neurons and that changes in receptor gene expression could be defined in a cell-specific pattern.
Single immunohistochemically labeled dysplastic and heterotopic neurons were microdissected from human focal cortical dysplasia specimens obtained during epilepsy surgery. Pyramidal neurons were microdissected from postmortem control cortex and from temporal cortex without dysplasia resected during temporal lobectomy. Poly (A) messenger RNA (mRNA) from single neurons was amplified, radiolabeled, and used to probe complementary DNA (cDNA) arrays containing GluR(1-6), NR(1A,1B), NR(2A-D), and GABA(A)Ralpha(1-6), and -Rbeta(1-3) subunit cDNAS: The relative hybridization intensities of each mRNA-cDNA hybrid were quantified by phosphorimaging.
GluR, NR, and GABA(A)R subunit mRNA expression did not differ between control neurons and nondysplastic epilepsy specimens. Expression of GluR(4), NR(2B), and NR(2C) subunit mRNA was increased, and NR(2A) and GABA(A)Rbeta(1) subunit mRNA was decreased in dysplastic compared with pyramidal and heterotopic neurons. In contrast, GABA(A)Ralpha(1), -Ralpha(2), and -Rbeta(2) as well as GluR(1) mRNA levels were reduced in both dysplastic and heterotopic neurons.
Differential expression of GluR, NR, and GABA(A)R mRNA in dysplastic and heterotopic neurons demonstrates cell specific gene transcription changes in focal cortical dysplasia. These results suggest that dysplastic and heterotopic neurons may be pharmacologically distinct and make differential contributions epileptogenesis in focal cortical dysplasia.
局灶性皮质发育不良的特征为皮质分层紊乱、发育异常和异位神经元，且与癫痫相关。发育异常和异位神经元在局灶性皮质发育不良癫痫发生中的作用尚不清楚，这些细胞的表型可能不同。作者推测，编码谷氨酸能（谷氨酸受体[GluR]和N-甲基-D-天冬氨酸NMDA受体[NR]）和γ-氨基丁酸A受体（GABA(A)R）亚基的基因在发育异常和异位神经元中的表达不同，且受体基因表达的变化可以通过细胞特异性模式来定义。
从癫痫手术中获取的人类局灶性皮质发育不良标本中显微切割出单免疫组化标记的发育异常和异位神经元。从死后对照皮质以及颞叶切除术中切除的无发育异常的颞叶皮质中显微切割出锥体细胞。对单个神经元的聚腺苷酸信使核糖核酸（mRNA）进行扩增、放射性标记，并用于探测包含GluR(1 - 6)、NR(1A,1B)、NR(2A - D)以及GABA(A)Rα(1 - 6)和 - Rβ(1 - 3)亚基互补脱氧核糖核酸（cDNA）的阵列：通过磷光成像对每个mRNA - cDNA杂交体的相对杂交强度进行定量。
对照神经元和无发育异常的癫痫标本之间GluR、NR和GABA(A)R亚基mRNA表达无差异。与锥体细胞和异位神经元相比，发育异常神经元中GluR(4)、NR(2B)和NR(2C)亚基mRNA表达增加，而NR(2A)和GABA(A)Rβ(1)亚基mRNA表达减少。相比之下，发育异常和异位神经元中GABA(A)Rα(1)、 - Rα(2)和 - Rβ(2)以及GluR(1) mRNA水平均降低。
发育异常和异位神经元中GluR、NR和GABA(A)R mRNA的差异表达表明局灶性皮质发育不良中存在细胞特异性基因转录变化。这些结果表明，发育异常和异位神经元在药理学上可能不同，并且在局灶性皮质发育不良的癫痫发生中起不同作用。
