Environmental influences on cortical development and plasticity via Cl^-homeostasis modulation

本研究的目的是检验以下假说的有效性：发育期的程序性Cl^-稳态使GABA兴奋并通过细胞迁移促进皮质生成，环境刺激引起的它的变化影响神经回路的形成和可塑性。我们建立了一种方法来区分径向迁移的谷氨酸细胞和切向迁移的GABA细胞在活切片中，通过转染HcRed基因到GAD 67-GFP基因敲入小鼠胚胎脑在体内。牛磺酸在胚胎脑中含量丰富，可能作为GABA_A受体的自分泌内源性激动剂参与放射性迁移，也可能作为旁分泌激动剂参与切向迁移。至于转染的异位KCC 2，表明其在体内径向迁移期间不起作用。因此，我们设计了最适合于干扰Cl^-转运蛋白转录过程的shRNA的碱基序列， ...更多信息 在边缘带内的通讯中，GABA和牛磺酸分别作为GABA_A和甘氨酸受体的内源性激动剂，促进边缘带内兴奋的扩散，而Cajal-Retzius细胞在放射状迁移中起重要作用。GABA_A和甘氨酸受体原本是抑制性的，但由于NKCC 1维持的高[Cl^-]_i而增加了兴奋性。然而，原本兴奋的谷氨酸受体没有参与。考虑到母体应激是对胚胎的环境刺激，我们建立了一种对母体施加限制应激的小鼠模型，从妊娠第8天到第17天，将母体限制在直径3cm、长9 cm的圆柱体中，每天6小时。与对照组相比，18日龄胚胎的体重和脑重均显著降低，表明母体应激对胚胎脑发育有影响。少

The aim of this study is to examine a validity of the hypothesis that a programmed Cl^- homeostasis of the developmental period renders GABA excitatory and promotes corticogenesis by cell migration, and that its change by environmental stimulation influence the neural circuit formation and plasticity. We established a method to distinguish between radially-migrating glutamate cells and tangentially-migrating GABA cells in living slices, by means of transfection of the HcRed gene into a GAD67-GFP knock-in mouse embryo brain in vivo. Taurine, abundantly contained in embryo brains, might act as autocrine endogenous agonist of GABA_A receptors for radial migration, and might also act as paracrine agonist for a signal to tangential migration. As for transfected ectopic KCC2, it was suggested that it did not function in vivo during radial migration. Therefore, we have designed the base sequence which was most suitable for shRNA which interfere a transcription process of a Cl^- transporter, a … More nd constructed an expression plasmid vector encoding it. Regarding the communication within the marginal zone containing the Cajal-Retzius cells which play an important role in radial migration, GABA and taurine worked as endogenous agonists of GABA_A and glycine receptors, respectively, that promoted a spread of excitation within the marginal zone. GABA_A and the glycine receptors, that were originally inhibitory, increased an excitability due to high [Cl^-]_i what was maintained by NKCC1. However, glutamate receptors which are originally excitatory did not participate. Considering maternal stress as environmental stimulation for embryos, we developed a mouse model of restriction stress to a mother, which were confined in a cylinder of 3cm diameter and 9cm in length for six hours/day from 8th to 17th gestational days. Both the body weight and the brain weight of embryos at day 18th were significantly decreased in comparison with control, indicating an influence to the embryonic brain development by maternal stress. Less