Structure-function relationships in rat medullary and cervical dorsal horns. II. Medullary dorsal horn cells.
Structure-function relationships in rat medullary and cervical dorsal horns. II. Medullary dorsal horn cells.
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DOI：
10.1152/jn.1986.55.6.1187
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发表时间：
1986-06
影响因子：
2.5
通讯作者：
W. Renehan;M. Jacquin;R. Mooney;R. Rhoades
中科院分区：
文献类型：
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作者：
W. Renehan;M. Jacquin;R. Mooney;R. Rhoades
在Nembutal麻醉大鼠，31个生理鉴定的髓背角（MDH）细胞用辣根过氧化物酶（HRP）标记。10只对一根或多根触须的偏转有反应。6个细胞仅通过保卫毛运动激活，6个通过保卫毛或触须的偏转激活，7个通过用锯齿状镊子捏面部皮肤激活。不同类别的低阈值细胞不能区分的基础上，他们的体细胞形态或层状分布。然而，由多根触须激活的神经元是独特的，其中一根将其轴突送入内侧丘系，三根投射到三叉神经脊髓束。只有保卫毛或触须加保卫毛的神经元都没有这样的投射。对伤害性刺激反应最好的细胞主要位于I、II和深V层，而由触须（e）和/或保卫毛偏转激活的神经元位于III、IV和浅V层。低阈值神经元通常具有相当厚的树突，很少有刺，而高阈值细胞往往具有较薄的树突，具有许多刺。此外，低阈值细胞的树突状乔木，在大多数情况下，密度比那些有害的细胞。神经元与下颌感受野位于背内侧部分的MDH;细胞与眼领域被发现在腹外侧的MDH，和上颌细胞之间。细胞敏感的偏转背mystyrus vibrissae和/或保卫毛位于腹侧的那些激活更腹毛。在头侧MDH中发现了具有头侧感受野的神经元，而尾侧迷走神经垫、耳周和眶周区域的毛激活的细胞位于尾侧MDH中。感受野类型，还没有报告三叉神经初级传入神经元：多触须;触须加警卫毛;和宽的动态范围。后两者可以解释为不同的初级传入类型到单个神经元的会聚。我们未能找到一个显着的树突面积（在横向平面）和触须的数量之间的关系表明，初级传入会聚可能不负责多触须感受野的合成。因此，MDH神经元之间的兴奋性连接可能是MDH中多个触须感受野的原因。
In Nembutal-anesthetized rats, 31 physiologically identified medullary dorsal horn (MDH) cells were labeled with horseradish peroxidase (HRP). Ten responded only to deflection of one or more vibrissae. Six cells were activated by guard hair movement only, six by deflection of guard hairs or vibrissa(e), and seven by pinch of facial skin with serrated forceps. Different classes of low-threshold cells could not be distinguished on the basis of their somadendritic morphologies or laminar distribution. Neurons activated by multiple vibrissae were unique, however, in that one sent its axon into the medial lemniscus, and three projected into the trigeminal spinal tract. None of the guard hair-only or vibrissae-plus-guard hair neurons had such projections. Cells that responded best to noxious stimulation were located mainly in laminae I, II, and deep V, while neurons activated by vibrissa(e) and/or guard hair deflection were located in layers III, IV, and superficial V. Low-threshold neurons generally had fairly thick dendrites with few spines, whereas high-threshold cells tended to have thinner dendrites with numerous spines. Moreover, the dendritic arbors of low-threshold cells were, for the most part, denser than those of the noxious cells. Neurons with mandibular receptive fields were located in the dorsomedial portion of the MDH; cells with ophthalmic fields were found in the ventrolateral MDH, and maxillary cells were interposed. Cells sensitive to deflection of dorsal mystacial vibrissae and/or guard hairs were located ventral to those activated by more ventral hairs. Neurons with rostral receptive fields were found in the rostral MDH, while cells activated by hairs of the caudal mystacial pad, periauricular, and periorbital regions were located in the caudal MDH. Receptive-field types were encountered that have not been reported for trigeminal primary afferent neurons: multiple vibrissae; vibrissae plus guard hairs; and wide dynamic range. The latter two can be explained by the convergence of different primary afferent types onto individual neurons. Our failure to find a significant relationship between dendritic area (in the transverse plane) and the number of vibrissae suggests that primary afferent convergence may not be responsible for the synthesis of the multiple vibrissae receptive field. Excitatory connections between MDH neurons may, therefore, account for multiple vibrissae receptive fields in the MDH.