Miller K E, Seybold V S
J Comp Neurol. 1987 Jan 8;255(2):293-304. doi: 10.1002/cne.902550212.
This study compared the distribution of methionine enkephalin-, dynorphin A 1-8-, and neurotensin-immunoreactive (IR) perikarya in laminae I and IV-VII of selected segments of lumbar spinal cord of cat(L5) and rat(4). Immunoreactive neurons for each peptide were found throughout the dorsal horn and dorsal lamina VII but were quantified only within laminae I and IV-VII. In lamina I, both large (greater than 20 micron) and small (less than 20 micron) IR neurons were identified. Large IR neurons for each peptide in both species resembled Waldeyer neurons studied by Golgi stain and were outnumbered by small IR neurons. Comparison among the laminae of the distribution of met-enkephalin IR neurons showed a similar pattern in the two species with the majority of IR neurons (greater than 65%) in laminae V and VI. Differences in laminar distribution occurred between species for the other peptides. Dynorphin IR neurons were greatest in number in lamina V in rat but greatest in number in laminae I and V in cat. Neurotensin IR neurons occurred predominantly in cat lamina I but were nearly equal in density in rat laminae I and VI. The topographic distribution of each peptide in laminae V and VI was similar between the two species with IR neurons occurring laterally in lamina V and more medially in lamina VI. Comparisons between species of the numbers of IR neurons/segment indicated distinct relationships for each peptide. The number of met-enkephalin IR neurons in laminae of cat L5 was generally two times greater than the number of IR neurons in the same laminae of rat L4, except in laminae I and IV, where the numbers were nearly equal. In contrast, the number of dynorphin IR neurons in cat laminae was generally one-half the number in rat, except in lamina I, where the number in cat was two times greater than rat. A high degree of variability occurred in laminar comparisons of neurotensin IR neurons. Neurotensin IR neurons in lamina I of cat outnumbered those of rat 2:1, but in laminae IV-VII, the ratio of cat to rat IR neurons varied from 1:1 to 1:20. The met-enkephalin, dynorphin, and neurotensin IR neurons quantified in this study may be interneurons or may serve as projection neurons to brainstem and/or thalamic nuclei. The observed differences in distribution may be relevant to differences in spinal cord physiology in the two species.
本研究比较了猫（L5）和大鼠（4）腰段脊髓选定节段I层以及IV - VII层中甲硫氨酸脑啡肽、强啡肽A 1 - 8和神经降压素免疫反应性（IR）神经元胞体的分布情况。在整个背角和背侧VII层均发现了每种肽的免疫反应性神经元，但仅对I层以及IV - VII层内的神经元进行了定量分析。在I层中，识别出了大型（大于20微米）和小型（小于20微米）IR神经元。两个物种中每种肽的大型IR神经元类似于用高尔基染色法研究的瓦尔代尔神经元，且数量少于小型IR神经元。甲硫氨酸脑啡肽IR神经元分布的层间比较显示，两个物种的模式相似，大多数IR神经元（大于65%）位于V层和VI层。其他肽在物种间的层分布存在差异。强啡肽IR神经元在大鼠的V层数量最多，但在猫的I层和V层数量最多。神经降压素IR神经元主要出现在猫的I层，但在大鼠的I层和VI层密度几乎相等。两个物种中每种肽在V层和VI层的地形分布相似，IR神经元在V层外侧出现，在VI层更靠内侧。物种间IR神经元/节段数量的比较表明每种肽存在明显的关系。猫L5层中甲硫氨酸脑啡肽IR神经元的数量通常比大鼠L4相同层中的IR神经元数量多两倍，但在I层和IV层中，数量几乎相等。相反，猫层中强啡肽IR神经元的数量通常是大鼠的一半，但在I层中，猫的数量比大鼠多两倍。神经降压素IR神经元的层间比较存在高度变异性。猫I层中的神经降压素IR神经元数量比大鼠多2:1，但在IV - VII层中，猫与大鼠IR神经元的比例从1:1到1:20不等。本研究中定量的甲硫氨酸脑啡肽、强啡肽和神经降压素IR神经元可能是中间神经元，或者可能作为投射神经元至脑干和/或丘脑核团。观察到的分布差异可能与两个物种脊髓生理学的差异有关。
