Absence of Meissner corpuscles in the digital pads of mice lacking functional TrkB
Absence of Meissner corpuscles in the digital pads of mice lacking functional TrkB
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DOI：
10.1016/j.brainres.2004.01.003
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发表时间：
2004-03-26
期刊：
影响因子：
2.9
通讯作者：
Vega, JA
中科院分区：
文献类型：
--
作者：
González-Martínez, T;Germaná, GP;Vega, JA
表达 TrkB 的感觉神经元似乎与触觉和其他辨别性感觉有关。因此，在功能性 TrkB 缺陷小鼠的三叉神经区域中，几种缓慢和快速适应的皮肤机械感受器以及肌梭减少或缺失。尚未分析这是否也发生在背根神经节的皮肤或肌肉区域。在这里，我们使用免疫组织化学和透射电子显微镜来分析 TrkB 基因编码突变对迈斯纳小体和帕西尼小体以及肌梭的影响。这些动物在出生后第 15 天和第 25 天进行了研究，因为此时检查的所有机械感受器都已完全发育。在野生型和 TrkB+/- 小鼠的指垫中发现了显示 S-100 蛋白免疫反应性的典型迈斯纳氏小体，而在 TrkB-/- 动物中则不存在。对于 Pacinian 小体，trkB 基因的突变不会改变免疫组织化学或超微结构特征。最后，在突变动物的肌梭中，梭内肌纤维和神经纤维的排列没有改变。然而，约 10% 的肌梭显示梭内细胞数量增加（6 至 12 个），并且由不止一根大髓鞘神经纤维提供。目前的结果强烈表明，背根神经节中表达 TrkB 的感觉神经元（如三叉神经节的感觉神经元）负责几种快速适应皮肤机械感受器（即迈斯纳小体）的发育和维持。 (C) 2004 Elsevier B.V. 保留所有权利。
The TrkB-expressing sensory neurons seem to be involved in touch and other discriminative sensibilities. Thus, several slowly and rapidly adapting cutaneous mechanoreceptors, as well as muscle spindles, are reduced or absent in the territory of the trigeminal nerve in functionally TrkB-deficient mice. Whether this also occurs in the cutaneous or muscular territories of dorsal root ganglia has not been analyzed. Here we used immunohistochemistry and transmission-electron microscopy to analyze the impact of a mutation in the gene coding for TrkB on Meissner and Pacinian corpuscles, and muscle spindles. The animals were studied at the post-natal days 15 and 25, because at this time all the mechanoreceptors examined are fully developed. Typical Meissner's corpuscles, displaying S-100 protein immunoreactivity, were found in the digital pads of wild-type and TrkB+/- mice whereas they were absent in the TrkB-/- animals. Regarding Pacinian corpuscles, the mutation in the trkB gene does not alter either the immunohistochemical or the ultrastructural characteristics. Finally, in muscle spindles the arrangement of the intrafusal muscle fibers and nerve fibers was unchanged in the mutated animals. Nevertheless, about 10% of muscle spindles showed increased number of the intrafusal cells (between 6 and 12) and were supplied by more than one large myelinic nerve fiber. The present results strongly suggest that TrkB-expressing sensory neurons in dorsal root ganglia, like those of the trigeminal ganglion, are responsible for the development and maintenance of several rapidly adapting cutaneous mechanoreceptors, i.e. Meissner's corpuscles. (C) 2004 Elsevier B.V. All rights reserved.