Zinc-rich transient vertical modules in the rat retrosplenial cortex during postnatal development
Zinc-rich transient vertical modules in the rat retrosplenial cortex during postnatal development
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DOI：
10.1016/j.neuroscience.2005.11.049
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发表时间：
2006-01-01
期刊：
影响因子：
3.3
通讯作者：
Rockland, KS
中科院分区：
文献类型：
--
作者：
Miró-Bernié, N;Ichinohe, N;Rockland, KS
大鼠压后皮质是高度互连的边缘回路的一部分，被认为在空间记忆中具有重要作用。有趣的是，颗粒压后皮质有一个非常独特的树突束系统，起源于胼胝体投射锥体神经元在第二层。这些可以检测到，早在出生后第5天，而且，虽然其功能的意义仍有待阐明，这些束的存在使得颗粒压后皮质一个有吸引力的模型系统，为广泛的发展和功能的调查。在这里，我们报告了四个结果有关的发展，在大鼠的颗粒压后皮质的模块化的皮质-皮质和丘脑-皮质连接相关的神经化学标记物的调查。重点放在锌，一个活动相关的物质与丘脑，非丘脑终止。1)锌在出生后早期发育过程中表现出短暂的强表达，但晚于上层束的出现（出生后第5天）。到出生后第11天至出生后第15天，锌染色达到了最复杂的模式;这样，第一层在切向和径向维度上都有一个精心设计的组织。可区分三个亚层（Ia-c层）：一个浅的薄层（Ia），具有斑片状的中度染色，周期性地侵入下层Ib（“漏斗”模块），一个宽度可变且染色较浅的中间带（Ib），以及一个深的薄层，具有重度和斑片状染色（Ic），在吻侧水平向上扩展到Ib层（作为“圆顶状”模块）。2)在出生后第15天，免疫组织化学方法显示，层Ia，B锌漏斗共定位与谷氨酸受体亚基2/3，GABA受体A型α 1亚基和丘脑-皮质标记，囊泡谷氨酸转运蛋白2。层Ic和锌圆顶样模块共同标记的皮质-皮质标记物，囊泡谷氨酸转运蛋白1和钙视网膜蛋白。3)通过电子显微镜进一步研究了Ia、B层锌漏斗与囊泡谷氨酸转运体2之间的空间一致性，证实了锌和囊泡谷氨酸转运体2在突触终扣中的共定位。锌和丘脑-皮质末梢的不寻常的共同定位被证实，在出生后第9天和出生后第13天的前背侧丘脑核中的神经元的锌的逆行运输，因此可以被认为是一个短暂的锌表达在丘脑-皮质终扣。在产后28天或以后未观察到这一点。4)出生后第18天，锌染色开始褪色，在所有层。在出生后第21天，重染色的锌在圆顶已完全消失。锌染色在la层和漏斗几乎消失后，出生后28天。在至少一个其他皮质区域（出生后第5天至出生后第14天的桶皮质IV层，出生后第9-11天达到最大值）报告了锌的瞬时表达。我们的结论是，锌的瞬时表达可以发生在边缘和感觉区，锌在皮质模块的下调可能与突触可塑性和发育过程中的重塑。(c)2005年IBRO。由爱思唯尔有限公司出版。保留所有权利。
The rat retrosplenial cortex is part of a heavily interconnected limbic circuit, considered to have an important role in spatial memory. Interestingly, the granular retrosplenial cortex has an exceptionally distinct system of dendritic bundles, originating from callosally projecting pyramidal neurons in layer II. These can be detected as early as postnatal day 5; and, although their functional significance remains to be elucidated, the existence of these bundles makes the granular retrosplenial cortex an attractive model system for a wide range of development and functional investigations. Here, we report four results concerning the development of modularity in the granular retrosplenial cortex in rats as investigated by neurochemical markers associated to cortico-cortical and thalamo-cortical connections. Emphasis is placed on zinc, an activity-related substance associated with glutamatergic, non-thalamic terminations. 1) Zinc shows a transient strong expression during early postnatal development, but later than the appearance of the upper layer bundles (at postnatal day 5). By postnatal day 11 to postnatal day 15 staining for zinc achieved its most complex pattern; such that layer I had an elaborate organization both in the tangential and radial dimensions. Three sublaminae were distinguished (layers Ia-c): a superficial, thin tier (Ia) with patchy, moderate staining which periodically intruded into the underlying layer Ib ("funnel" modules), a middle band of variable width and light staining (Ib), and a deep, thin band with heavy and patchy staining (Ic) which, at rostral levels, spread upward into layer Ib (as "dome-like" modules). 2) At postnatal day 15, immunohistochemical methods showed that layers Ia, b zinc-funnels were co-localized with glutamate receptor subunits 2/3, GABA receptor type A alpha 1 subunit and the thalamo-cortical marker, vesicular glutamate transporter 2. Layer Ic and the zinc dome-like modules were co-labeled for the cortico-cortical marker, vesicular glutamate transporter 1 and calretinin. 3) The spatial coincidence between zinc funnels in layers Ia, b and vesicular glutamate transporter 2 was further investigated by electron microscopy, which demonstrated co-localization of zinc and vesicular glutamate transporter 2 in synaptic boutons. The unusual co-localization of zinc and thalamo-cortical terminations was confirmed by retrograde transport of zinc to neurones in the anterodorsal thalamic nucleus at postnatal day 9 and postnatal day 13, and can thus be considered a transient zinc expression in thalamo-cortical boutons. This was not observed at postnatal day 28 or later. 4) After postnatal day 18, zinc staining started to fade in all layers. Before postnatal day 21, the heavy staining for zinc in the domes had completely disappeared. Zinc staining in layer la and the funnels virtually disappeared after postnatal day 28. A transient expression of zinc is reported in at least one other cortical area (layer IV of barrel cortex from postnatal day 5 to postnatal day 14, maximal at postnatal days 9-11). We conclude that the transient expression of zinc can occur in both limbic and sensory areas, and that down-regulation of zinc in cortical modules might be related to synaptic plasticity and remodeling during development. (c) 2005 IBRO. Published by Elsevier Ltd. All rights reserved.