MORPHOLOGY AND TOPOGRAPHY OF IDENTIFIED PRIMARY AFFERENTS IN TRIGEMINAL SUBNUCLEI PRINCIPALIS AND ORALIS
MORPHOLOGY AND TOPOGRAPHY OF IDENTIFIED PRIMARY AFFERENTS IN TRIGEMINAL SUBNUCLEI PRINCIPALIS AND ORALIS
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DOI：
10.1152/jn.1993.70.5.1911
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发表时间：
1993-11-01
影响因子：
2.5
通讯作者：
PANNETON, WM
中科院分区：
文献类型：
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作者：
JACQUIN, MF;RENEHAN, WE;PANNETON, WM
1. 采用轴突内记录、感受野定位、辣根过氧化物酶注射、细胞色素氧化酶染色以及计算机辅助重建/形态测量方法，来阐明正常成年大鼠三叉神经初级传入侧支的结构和分布。先前的研究集中在三叉神经脑干中极核和尾核。本研究在此基础上扩展到其余两个亚核，即主核（PrV）和口核（SpVo），对37只成年大鼠的66条轴突的侧支进行了研究。在9只大鼠中，对3 - 5条轴突进行染色，以便对不同纤维在核内进行比较。定量分析仅限于触须敏感纤维。
2. 所有轴突传导迅速，具有小的低阈值感受野。大多数对触须偏转有反应（n = 47）；其余的对保护毛偏转、施加于有毛皮肤、无毛皮肤、舌黏膜或门齿的轻柔压力，或下颌运动有反应。所有轴突都在三叉神经感觉根中下行，其中一些分支为上升支和下降支。每条染色良好的纤维在PrV和SpVo中都产生横向的侧支。
3. 在PrV和SpVo内，具有不同适应特性和感受野的纤维具有难以区分的侧支形态。单个轴突的树突分支在头尾方向上是不连续的，相对于中极核和尾核的侧支较小，其分布范围和地形组织方式与细胞色素氧化酶和大量标记的初级传入染色模式一致。在SpVo和PrV尾侧，图谱是倒置的，鼻子指向内侧。在PrV头侧，图谱旋转90度，使得鼻子指向上方。
4. 轴突在三叉神经脑干复合体的头尾轴上具有不同的定量特性。尽管树突分支在PrV和SpVo中所覆盖的横向区域相似，但PrV头侧三分之一处的侧支具有相对较低的终扣密度。PrV尾侧三分之二处的树突分支具有最高的终扣密度。SpVo中的树突分支在大小和形状上往往比PrV尾侧更具变化性，并且其终扣数量明显低于PrV。
5. 在PrV中，树突分支主要局限于与躯体定位相对应的细胞色素氧化酶斑块内，避免了相邻触须投射的显著重叠。在SpVo中，终止部位没有那么严格的局限，在对多条轴突进行染色的情况下，获得了许多触须传入纤维在行内和行间重叠的例子。
6. 这些以及先前的数据表明，外周和中枢靶标因素影响大鼠三叉神经脑干复合体中的侧支形态，并且PrV和SpVo中细胞的生理差异反映了这两个区域中不同的初级传入分支模式。这些以及关于PrV树突树几何形状的其他数据表明，PrV二级神经元的感受野大小存在解剖学基础。
1. Intra-axonal recording, receptive field mapping, horseradish peroxidase injection, cytochrome oxidase staining, and computer-assisted reconstruction/morphometric methods were used to elucidate the structure and topography of trigeminal primary afferent collaterals in the normal adult rat. Prior studies focused on trigeminal brain stem subnuclei interpolaris and caudalis. This work is extended here to the remaining 2 subnuclei, principalis (PrV) and oralis (SpVo), where collaterals from 66 axons in 37 adult rats were studied. In nine rats, three to five axons were stained for within-nucleus comparisons of different fibers. Quantitative analyses were restricted to vibrissa sensitive fibers. 2. All of the axons conducted rapidly with small, low-threshold receptive fields. The majority responded to vibrissa deflection (n = 47); the remainder responded to guard hair deflection; gentle pressure applied to hairy skin, glabrous skin, lingual mucosa, or an incisor; or jaw movement. All descended in the trigeminal sensory root where some bifurcated into ascending and descending branches. Each well-stained fiber gave rise to transversely oriented collaterals in PrV and SpVo. 3. Within PrV and SpVo, fibers with differing adaptation properties and receptive fields had indistinguishable collateral morphologies. Arbors from single axons were rostrocaudally discontinuous, small relative to collaterals in subnuclei interpolaris and caudalis, circumscribed and topographically organized in a manner consistent with cytochrome oxidase and bulk-labeled primary afferent staining patterns. In SpVo and caudal PrV, the map is inverted with the nose pointing medially. In rostral PrV, the map turns 90-degrees such that the nose points dorsally. 4. Axons had different quantitative properties along the rostrocaudal axis of the trigeminal brain stem complex. Whereas arbors subtended similar transverse areas throughout PrV and SpVo, collaterals in the rostral third of PrV had a relatively low bouton density. Arbors in the caudal two thirds of PrV had the highest bouton density. Arbors in SpVo tended to be more variable in size shape than those of caudal PrV, and their bouton numbers were significantly lower than in PrV. 5. In PrV, arbors were largely confined to somatotopically corresponding cytochrome oxidase patches, precluding significant overlap of neighboring whisker projections. In SpVo, termination sites were not as strictly confined and numerous examples of within- and between-row overlap were obtained for whisker afferents in cases where multiple axons were stained.6. These and prior data suggest that peripheral and central target factors influence collateral morphology in the rat trigeminal brain stem complex, and that physiological distinctions between cells in PrV and SpVo reflect different primary afferent arborization patterns in these two regions. These and other data on the geometry of PrV dendritic trees suggest an anatomic substrate for receptive field size in PrV second-order neurons.