大鼠大脑皮层运动区生物素化葡聚糖胺神经示踪标记的全景和局部组织学观察

doi:10.3969/j.issn.1006-7795.2025.01.014

摘要/Abstract

摘要： 目的采用传统生物素化葡聚糖胺(biotinylated dextran amine，BDA)神经示踪技术结合全景和局部显微镜成像技术显示大脑初级运动皮层(primary motor cortex，M1)锥体神经元胞体及其轴突沿皮质脊髓束投射的详细组织学特征。方法使用脑立体定位系统将100 nL 10%（质量分数）BDA (相对分子质量10 000)注射到大鼠M1脑区，通过全景组织扫描分析系统连续追踪BDA神经标记沿皮质脊髓束通路在脑和脊髓组织中的分布，通过激光共聚焦显微镜详细观察BDA神经标记的组织学特征。结果采用全景组织扫描分析系统更便于对BDA神经标记的总体分布进行观察，在M1注射点周围，BDA标记显示在第Ⅴ层锥体神经元胞体；在注射点对侧对应的M1脑区以及同侧的初级感觉皮层，BDA主要显示顺行标记的神经纤维同时伴有少量逆行标记的神经元胞体；在大脑皮层以下的区域，BDA均显示顺行标记的神经纤维，包括神经纤维束和神经纤维终末，其投射区域有同侧的纹状体、丘脑、内囊、大脑脚和脑桥，以及经脑干锥体交叉后到达对侧的脊髓。在此基础上，采用共聚焦显微成像及其三维重建操作系统可以实现对BDA神经标记的局部显微特征进行详细的观察和解析，其中包括逆行标记的神经元胞体、树突及其树突棘，以及顺行标记的神经纤维及其终末。结论传统的BDA神经示踪技术与全景组织扫描分析和共聚焦显微成像技术的有机结合可以成为从全景到局部对长投射神经环路观察和解析的有效途径并具有广泛的应用前景。

关键词: 运动皮层, 神经环路, 皮质脊髓束, 全景扫描, 显微成像, 三维重建

Abstract: Objective To reveal the detailed histological characteristics of pyramidal neuron cell bodies and their axonal projections along the corticospinal tract in the primary motor cortex (M1) of the brain, by using the biotinylated dextran amine (BDA) neural tracing technique combined with panoramic and local microscopic imaging technologies. Methods A total of 100 nL of 10% BDA (10,000 molecular weight) was injected into M1 region using stereotaxic system. The distribution of BDA labeling along the corticospinal tract was continuously tracked with panoramic tissue scanning analysis system. Detailed observations of the histological characteristics of BDA labeling were carried out with laser confocal microscope. Results It is more convenient to observe the overall distribution of BDA neural labeling by using the panoramic tissue scanning analysis system. Around the injection site in M1, the BDA labeling was shown in the somas of pyramidal neurons in layer V. In the M1 region corresponding to the contralateral site of the injection site and ipsilateral primary sensory cortex, BDA showed predominantly the anterograde labeled nerve fibers accompanied by a few retrograde labeled neurons. Besides, BDA labeled nerve fibers-including bundles and terminals-projecting to regions such as the ipsilateral striatum, thalamus, internal capsule, cerebral peduncle, and pons, and further reaching the contralateral spinal cord via the brainstem pyramidal decussation. Confocal microscopy and its 3D reconstruction system facilitated detailed analysis of the local microscopic features of BDA labeling, revealing retrograde labeled neuron cell bodies, dendrites and their spines, as well as anterograde labeled nerve fibers and their terminals. Conclusions These findings demonstrated that the integration of traditional BDA neural tracing with panoramic tissue scanning analysis and confocal microscopy provided an effective approach to the observation and analysis of long-projection neural circuits from panoramic to local perspectives, with broad application prospects.

Key words: motor cortex, neural circuits, corticospinal tract, panoramic scanning, microscopic imaging, three-dimensional reconstruction

中图分类号:

Q189

陆嘉盈, 徐东升, 崔晶晶, 王雨晴, 苏雨昕, 刘一寒, 王佳, 白万柱. 大鼠大脑皮层运动区生物素化葡聚糖胺神经示踪标记的全景和局部组织学观察[J]. 首都医科大学学报, 2025, 46(1): 83-90.

Lu Jiaying, Xu Dongsheng, Cui Jingjing, Wang Yuqing, Su Yuxin, Liu Yihan, Wang Jia, Bai Wanzhu. Panoramic and local histological observations of biotinylated dextran amine neural tracer labeling in the motor cortex of rat brain[J]. Journal of Capital Medical University, 2025, 46(1): 83-90.

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