Transient synaptic zinc-positive thalamocortical terminals in the developing barrel cortex
Transient synaptic zinc-positive thalamocortical terminals in the developing barrel cortex
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DOI：
10.1111/j.1460-9568.2006.05000.x
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发表时间：
2006-08-01
影响因子：
3.4
通讯作者：
Rockland, Kathleen S.
中科院分区：
文献类型：
--
作者：
Ichinohe, Noritaka;Potapov, Daniel;Rockland, Kathleen S.
在大鼠桶状皮质中，从出生后第9天（P）到P12，第4层具有瞬时高密度的锌阳性终末[P.W.兰德公司Shamalla-Hannah（2002）J. Comp. Neurol.，447，43-56]。这些终端已被提出起源于皮质-皮质连接，但其确切的起源是未知的。为了确定它们的来源，我们将亚硒酸钠注射到两只成年大鼠和32只幼鼠的桶状皮质中，从P5到P28。正如预测的那样，在注射部位周围和远处的皮质区域可见丰富的锌阳性皮质投射神经元。从P9到P13，然而，神经元逆行标记的亚硒酸锌发生在丘脑，在地形适当的区域的腹后内侧核（VPM）和后核（Po）。因为以前没有锌阳性感觉丘脑皮质连接的报告，我们寻求证实这一意外的发现，通过电子显微镜。这揭示了在第4层和第1层的一个子集，积极的锌和囊泡谷氨酸转运蛋白2，丘脑皮质终端使用的蛋白质。最后，在另外9只大鼠中，我们进行了锌转运蛋白3 mRNA的原位杂交。在P10时在VPM和Po中检测到中等信号，但到P28时消失。相比之下，一个强烈的信号是明显的前背核，其中项目的边缘区，并坚持在P28。感觉丘脑中短暂的锌阳性终止的时间大致与出生后第二周中期的探索和搅拌行为的开始相吻合;这表明锌对与活动相关的电路完善很重要。
In rat barrel cortex, layer 4 has a transiently high density of zinc-positive terminations from postnatal day (P)9 to P12 [P. W. Land & L. Shamalla-Hannah (2002) J. Comp. Neurol., 447, 43-56]. These terminations have been proposed to originate from cortico-cortical connections, but their exact origin is unknown. To determine their sources, we injected sodium selenite into the barrel cortex of two adult rats and 32 pups, from P5 to P28. As predicted, abundant zinc-positive cortically projecting neurons were visible around the injection sites and in distant cortical areas. From P9 to P13, however, neurons retrogradely labeled by zinc selenite occurred in the thalamus, in topographically appropriate regions of the ventroposterior medial (VPM) and posterior nuclei (Po). Because there are no previous reports of zinc-positive sensory thalamocortical connections, we sought corroboration of this unexpected finding by electron microscopy. This revealed a subset of boutons in layers 4 and 1, positive for both zinc and vesicular glutamate transporter 2, a protein used by thalamocortical terminations. Finally, in an additional nine rats, we carried out in situ hybridization for zinc transporter 3 mRNA. Moderate signal was detected in VPM and Po at P10, but this disappeared by P28. In contrast, a strong signal was apparent in the anterodorsal nucleus, which projects to limbic areas, and this persisted at P28. The timing of the transient zinc-positive terminations in the sensory thalamus roughly coincides with the onset of exploratory and whisking behavior in the middle of the second postnatal week; and this suggests zinc is important for activity-related refinement of circuitry.