Center for Integrative Brain Research, Seattle Children's Research Institute, Seattle, Washington, USA.
Epilepsia. 2010 Aug;51(8):1456-67. doi: 10.1111/j.1528-1167.2009.02491.x. Epub 2010 Feb 3.
Expression of the protein subunits that make up the γ-aminobutyric acid (GABA)(A) receptor pentamer is known to change during postnatal brain development in animal models. In the present study, analysis of cortical GABA(A) subunit expression was performed in control human tissue obtained from infancy through adolescence, and was compared to that from similarly aged children with intractable focal epilepsy.
Twenty frozen pediatric control and 25 epileptic neocortical specimens were collected. The membrane fractions were isolated and subjected to quantitative western blot analysis. Subunit expression was correlated with clinical factors including age, pathology, and medication exposure.
In control cortical samples, α₁ and γ₂ GABA(A) receptor subunits exhibited low expression in infancy, which increased over the first several years of life and then stabilized through adolescence. In contrast, α₄ subunit expression was higher in infants than in older children. The level of the chloride transporter KCC2 increased markedly with age, whereas that of NKCC1 decreased. These patterns were absent in the children with epilepsy, both in those with focal cortical dysplasia and in those with cortical gliosis. Although there was marked variability in GABA(A) receptor subunit expression among the children with epilepsy, identifiable patterns of subunit expression were found in each individual child.
Maturation of cortical GABA(A) receptor subunit expression continues over the first several years of postnatal human development. Intractable focal epilepsy in children is associated with disruption of this normal developmental pattern. These findings have significant implications for the treatment of children with medications that modulate GABA(A) receptor function.
在动物模型中，已知组成γ-氨基丁酸（GABA）（A）受体五聚体的蛋白质亚基的表达在出生后大脑发育过程中会发生变化。在本研究中，我们分析了来自婴儿期到青春期的正常人类脑组织中的皮质 GABA（A）亚基表达，并将其与具有难治性局灶性癫痫的同龄儿童的表达进行了比较。
收集了 20 份冷冻的儿科对照组和 25 份癫痫性新皮质标本。分离膜部分并进行定量 Western blot 分析。亚基表达与临床因素（包括年龄、病理学和药物暴露）相关联。
在正常皮质样本中，α₁和γ₂ GABA（A）受体亚基在婴儿期表达量较低，在生命的前几年增加，然后在青春期稳定。相比之下，α₄ 亚基在婴儿期的表达量高于儿童期。氯离子转运蛋白 KCC2 的水平随年龄显著增加，而 NKCC1 的水平则降低。这些模式在癫痫儿童中均不存在，无论是局灶性皮质发育不良还是皮质神经胶质增生的儿童。尽管癫痫儿童的 GABA（A）受体亚基表达存在明显的变异性，但在每个个体儿童中都发现了可识别的亚基表达模式。
皮质 GABA（A）受体亚基表达的成熟在人类出生后的前几年持续进行。儿童的难治性局灶性癫痫与这种正常发育模式的破坏有关。这些发现对使用调节 GABA（A）受体功能的药物治疗儿童具有重要意义。
