Refinement of Thalamocortical Arbors and Emergence of Barrel Domains in the Primary Somatosensory Cortex: A Study of Normal and Monoamine Oxidase A Knock-Out Mice
Refinement of Thalamocortical Arbors and Emergence of Barrel Domains in the Primary Somatosensory Cortex: A Study of Normal and Monoamine Oxidase A Knock-Out Mice
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初级体感皮层丘脑皮质乔木的细化和桶状结构域的出现：正常小鼠和单胺氧化酶 A 敲除小鼠的研究
作者：
Alexandra Rebsam;I. Seif;P. Gaspar
在啮齿动物的初级躯体感觉皮质中，丘脑皮质轴突(TCA)被组织成与外围功能单位相对应的簇。在这些轴突周围，第四层的神经元聚集成桶状。为了了解这种组织是如何出现的，我们分析了不形成桶的小鼠、单胺氧化酶A敲除(MAOA-KO)和MAOA/5-HT1B受体双KO小鼠的TCA发育，这些小鼠的桶野恢复了。我们发现TCA在出生当天就已经达到了大脑皮层第四层。从出生后第0天(P0)到第二天(P2)，它们在这一层中均匀分布，并在第IV层二次结合成桶状域，持续3d(P3-P5)，在更深的层中没有预构图。在MAOA-KO小鼠中，TC投射的均匀分布保持不变，没有轴突簇出现。在注射碳菁后，追踪到个别的三氯乙酸树枝。在P1，三氯甲烷的分枝较差，覆盖的切向宽度可变，包括一到两个预期的桶。在P7时，第四层的TCA分支数量增加了10倍，并限制在一个桶内。在MAOA-KO小鼠中，第四层的TCA末端分支减少了50%，切线范围增加了40%。在MAOA/5-HT1B双基因敲除小鼠中，这些缺陷被纠正，表明突触前5-HT1B受体对轴突分支的影响。我们的结果表明，MAOA-KO小鼠的桶缺陷表型是由于其靶层IV中TCA乔木的变化细化所致，涉及出生后早期的分支细化和侧支收缩。
In the rodent primary somatosensory cortex, the thalamocortical axons (TCAs) are organized into clusters that correspond to functional units in the periphery. Around these axons, neurons in layer IV aggregate as barrels. To understand how this organization emerges, we analyzed TCA development in mice that do not form barrels, the monoamine oxidase A knock-out (MAOA-KO), and in MAOA/5-HT1Breceptor double-KO mice, which have a restored barrel field. We show that TCAs already attain cortical layer IV on the day of birth. They are uniformly distributed in this layer from postnatal day 0 (P0) to P2 and secondarily coalesce into barrel domains in layer IV, over a 3 d period (P3–P5), with no prepatterning in the deeper layers. In MAOA-KO mice, the uniform distribution of the TC projection is maintained, and no axon clusters emerge. Individual TCA arbors were traced after carbocyanine injections. At P1, TCAs were poorly branched and covered variable tangential widths, encompassing one to two prospective barrels. At P7 the number of TCA branches increased 10-fold in layer IV and became restricted to one barrel. In MAOA-KO mice, there was a 50% reduction of the TCA terminal branches in layer IV, with a 40% increase in their tangential extent. These defects were corrected in the MAOA/5-HT1B double knock-out mice, indicating an effect of the presynaptic 5-HT1B receptor on axon branching. Our results indicate that the barrel-deficient phenotype of MAOA-KO mice results from an altered refinement of the TCA arbors in their target layer IV, involving branch elaboration and collateral retraction during early postnatal life.
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影响因子：
3.7
作者：
Senft, Stephen L.;Woolsey, Thomas A.
通讯作者：
Woolsey, Thomas A.
影响因子：
56.9
作者：
CASES, O;SEIF, I;DEMAEYER, E
通讯作者：
DEMAEYER, E
影响因子：
56.9
作者：
Bishop, KM;Goudreau, G;O'Leary, DDM
通讯作者：
O'Leary, DDM
DOI：
10.1073/pnas.96.16.9397
发表时间：
1999-08-03
影响因子：
11.1
作者：
Maier, DL;Mani, S;Meiri, KF
通讯作者：
Meiri, KF