Kilb W, Luhmann H J
Institut für Neurophysiologie, Heinrich-Heine-Universität Düsseldorf, Postfach 101007, D-40001 Düsseldorf, Germany.
Eur J Neurosci. 2001 Apr;13(7):1387-90. doi: 10.1046/j.0953-816x.2001.01514.x.
Cajal-Retzius cells are among the first neurons appearing during corticogenesis, and play an important role in the establishment of cortical lamination. The variety of neurotransmitter receptors recently found on these cells imply that they are integrated in the neonatal cortical network. To investigate the presence and properties of spontaneous synaptic activity we performed whole-cell patch-clamp recordings from visually identified and biocytin-labelled Cajal-Retzius cells in a tangential slice preparation of neonatal rat cerebral cortex (postnatal days P0-P5). Spontaneous postsynaptic currents (sPSCs) could be observed in about 23% of the cells using a pipette solution containing 136 m M Cl-. The sPSCs occurred at a low frequency (0.07 +/- 0.07 Hz, n = 42 cells), had an average amplitude of 24.3 +/- 12.4 pA (n = 415 events) and could not be divided in subpopulations according to their amplitude distribution or kinetic properties. The sPSCs were blocked by the GABAA antagonist bicuculline (100 microM), while the glutamatergic antagonists (+/-)-2-amino-5-phosphonopentatonic acid (APV, 30 microM) and 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX, 10 microM), as well as tetrodotoxin (1-2 microM), a blocker of voltage-gated sodium-currents, had no significant effect on sPSCs. The incidence rate of sPSCs declined within the age of the rats and no sPSCs could be observed after P4. These results suggest that Cajal-Retzius cells transiently receive action potential-independent and GABA(A) receptor-mediated spontaneous synaptic input, which may contribute to the refinement of cortical circuits.
卡哈尔-雷茨乌斯细胞是皮质发生过程中最早出现的神经元之一，在皮质分层的建立中发挥重要作用。最近在这些细胞上发现的多种神经递质受体表明它们整合于新生皮质网络中。为了研究自发突触活动的存在及其特性，我们在新生大鼠大脑皮质（出生后第0 - 5天）的切线切片标本中，对视觉识别并用生物胞素标记的卡哈尔-雷茨乌斯细胞进行了全细胞膜片钳记录。使用含有136 mM Cl-的微电极内液，在约23%的细胞中可观察到自发突触后电流（sPSC）。sPSC出现频率较低（0.07±0.07 Hz，n = 42个细胞），平均幅度为24.3±12.4 pA（n = 415个事件），且根据其幅度分布或动力学特性无法分为亚群。sPSC被GABAA拮抗剂荷包牡丹碱（100 μM）阻断，而谷氨酸能拮抗剂（±）-2-氨基-5-磷酸戊酸（APV，30 μM）、6-氰基-7-硝基喹喔啉-2,3-二酮（CNQX，10 μM）以及电压门控钠电流阻滞剂河豚毒素（1 - 2 μM）对sPSC无显著影响。sPSC的发生率在大鼠年龄增长过程中下降，在出生后第4天之后未观察到sPSC。这些结果表明，卡哈尔-雷茨乌斯细胞短暂地接受与动作电位无关且由GABA(A)受体介导的自发突触输入，这可能有助于皮质回路的精细化。
