Cheng Qing, Yeh Pamela W L, Yeh Hermes H
Department of Physiology, Dartmouth Medical School, Dartmouth-Hitchcock Medical Center, One Medical Center Drive, Lebanon, NH 03756, USA.
Eur J Neurosci. 2006 Oct;24(8):2145-51. doi: 10.1111/j.1460-9568.2006.05122.x.
Cajal-Retzius cells are implicated in regulating neuronal migration and lamination during corticogenesis. In rodents, Cajal-Retzius cells are transient, being prevalent in the marginal zone of the embryonic neocortex and declining over the first two postnatal weeks. While studies have examined in postnatal neocortex the properties of GABA(A) receptors in Cajal-Retzius cells, less is known about their disposition at embryonic stages. Here, we combined patch-clamp electrophysiology and single-cell mRNA profiling to probe the expression of GABA(A) receptors in Cajal-Retzius cells. In embryonic neocortical slices, GABA elicited GABA(A) receptor-mediated current responses that were diazepam-insensitive and inhibited by Zn(2+), a pharmacological profile consistent with expression of gamma-less GABA(A) receptor isoforms. Non-Cajal-Retzius cells in the same embryonic slices, on the other hand, were robustly potentiated by diazepam and were insensitive to Zn(2+), typical of gamma-containing GABA(A) receptor isoforms, as were Cajal-Retzius cells in the postnatal neocortex. Single-cell mRNA profiling and immunohistochemistry confirmed expression of GABA(A) receptor gamma subunit transcript and protein, respectively, in individual reelin-expressing cells in the postnatal cortex but not in their embryonic counterparts. We conclude that Cajal-Retzius cells express gamma-less GABA(A) receptors at embryonic stages and switch to expressing gamma-containing GABA(A) receptor isoforms during postnatal neocortical development.
卡哈尔-雷茨尤斯细胞在皮质发生过程中参与调节神经元迁移和分层。在啮齿动物中，卡哈尔-雷茨尤斯细胞是短暂存在的，在胚胎新皮质的边缘区普遍存在，并在出生后的前两周内减少。虽然已有研究检测了出生后新皮质中卡哈尔-雷茨尤斯细胞上GABA(A)受体的特性，但对于它们在胚胎阶段的分布情况了解较少。在此，我们结合膜片钳电生理学和单细胞mRNA分析来探究卡哈尔-雷茨尤斯细胞中GABA(A)受体的表达。在胚胎新皮质切片中，GABA引发了GABA(A)受体介导的电流反应，这些反应对安定不敏感且被Zn(2+)抑制，这种药理学特征与无γ亚基的GABA(A)受体亚型的表达一致。另一方面，同一胚胎切片中的非卡哈尔-雷茨尤斯细胞被安定强烈增强，且对Zn(2+)不敏感，这是含γ亚基的GABA(A)受体亚型的典型特征，出生后新皮质中的卡哈尔-雷茨尤斯细胞也是如此。单细胞mRNA分析和免疫组织化学分别证实了出生后皮质中单个表达reelin的细胞中存在GABA(A)受体γ亚基转录本和蛋白，但在它们的胚胎对应物中则没有。我们得出结论，卡哈尔-雷茨尤斯细胞在胚胎阶段表达无γ亚基的GABA(A)受体，并在出生后新皮质发育过程中转变为表达含γ亚基的GABA(A)受体亚型。
