Micevych P E, Coquelin A, Arnold A P
J Comp Neurol. 1986 Jun 8;248(2):235-44. doi: 10.1002/cne.902480206.
The purpose of the present study was to identify chemically some potential inputs to lumbar motoneurons of the rat in the spinal nucleus of the bulbocavernosus, ventral motor pool, dorsolateral nucleus, and retrodorsolateral nucleus. Substance P-like immunoreactivity and serotonin-like immunoreactivity were found in all four motor nuclei, with dense immunoreactive profiles surrounding motoneurons and their processes. Enkephalin-like immunoreactivity was restricted to the sexually dimorphic nuclei, the spinal nucleus of the bulbocavernosus, and the dorsolateral nucleus. Within the spinal nucleus of the bulbocavernosus, enkephalin-like immunoreactive profiles were apposed to the processes of motoneurons but not their somata. In contrast, enkephalin-like immunoreactivity surrounded motoneuron somata in the medial part but not the lateral part of the dorsolateral nucleus, in the location of motoneurons projecting to the ischiocavernosus muscle. Moreover, the density of serotonin-like immunoreactivity was also greater in the medial part of the dorsolateral nucleus. On the basis of the chemo-architecture and the connections of the dorsolateral nucleus, we suggest the division of this motor column into a medial part composed of ischiocavernosus motoneurons surrounded by enkephalin- and serotonin-like immunoreactivity and a lateral part that contains neurons that project to the sphincter urethrae muscle. Total spinal transection severely depleted both serotonin-like and substance P-like material in the lumbar ventral horn. No changes in the distribution of enkephalin-like immunoreactivity were observed following this lesion. It is therefore suggested that in the ventral horn, substance P- and serotonin-like material are derived from supraspinal tracts, whereas enkephalin-like material is derived from intrinsic nerve cell bodies of the spinal cord.
本研究的目的是从化学角度确定大鼠延髓海绵体核、腹侧运动池、背外侧核和背外侧后核中腰运动神经元的一些潜在传入神经。在所有四个运动核中均发现了P物质样免疫反应性和5-羟色胺样免疫反应性，运动神经元及其突起周围有密集的免疫反应性轮廓。脑啡肽样免疫反应性仅限于性二态核、延髓海绵体核和背外侧核。在延髓海绵体核内，脑啡肽样免疫反应性轮廓与运动神经元的突起相邻，但不与它们的胞体相邻。相比之下，在背外侧核内侧部分而非外侧部分，脑啡肽样免疫反应性围绕着运动神经元胞体，此处的运动神经元投射到坐骨海绵体肌。此外，背外侧核内侧部分的5-羟色胺样免疫反应性密度也更高。基于背外侧核的化学结构和连接，我们建议将这个运动柱分为内侧部分和外侧部分，内侧部分由被脑啡肽样和5-羟色胺样免疫反应性包围的坐骨海绵体运动神经元组成，外侧部分包含投射到尿道括约肌的神经元。完全脊髓横断严重耗尽了腰腹角中的5-羟色胺样和P物质样物质。此损伤后未观察到脑啡肽样免疫反应性分布的变化。因此，有人提出在腹角中，P物质样和5-羟色胺样物质来自脊髓上的神经束，而脑啡肽样物质来自脊髓的内在神经细胞体。
