Miller K E, Seybold V S
Department of Cell Biology and Neuroanatomy, University of Minnesota, Minneapolis 55455.
J Comp Neurol. 1989 Jan 22;279(4):619-28. doi: 10.1002/cne.902790409.
This study examined the number of met-enkephalin, dynorphin A 1-8, and neurotensin immunoreactive (IR) neurons in the marginal zone (lamina I) at one thoracic (T8:cat,T9:rat), one midlumbar (L5:cat,L4:rat), and one lower lumbar or sacral (S1:cat,L6:rat) spinal cord segment in the cat and rat. Marginal zone IR neurons ranged 10-70 microns in diameter in cats and 10-50 microns in rats and were flattened, pyramidal, fusiform, or polygonal in morphology. Immunoreactive neurons for each peptide in both species were found in the marginal zone at all spinal levels, but with a differential segmental distribution. The average number of IR neurons per 50-microns section generally was lowest in thoracic cord and greatest in lower lumbar/sacral cord for all peptides. For enkephalin and dynorphin, the estimated total number of IR neurons per segment and number of IR neurons per volume (mm3) generally were lowest in the midlumbar segments and highest in the thoracic and lower lumbar/sacral cord. For neurotensin, the estimated total number of neurons per segment remained lowest in the thoracic and largest in the lower lumbar/sacral cord. The number of neurotensin IR neurons per volume was equal in the thoracic and midlumbar cord, but remained highest at lower lumbar/sacral levels. The IR neurons quantified in this study may be interneurons or may serve as supraspinal projection neurons. The large number of IR neurons observed in segments receiving a relatively large visceral afferent input suggests that some of these neurons may be involved in visceral sensory processing. In addition, the segmental distribution of the IR neurons indicates that physiological and pharmacological studies on the effects of opioid and/or neurotensin peptides should be interpreted in light of the spinal segment(s) investigated.
本研究检测了猫和大鼠的一个胸段（猫为T8，大鼠为T9）、一个中腰段（猫为L5，大鼠为L4）以及一个下腰段或骶段（猫为S1，大鼠为L6）脊髓节段边缘区（I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）神经元的数量。猫的边缘区IR神经元直径为10 - 70微米，大鼠的为10 - 50微米，其形态扁平、呈锥形、梭形或多边形。在两个物种的所有脊髓节段的边缘区均发现了每种肽的免疫反应性神经元，但节段分布存在差异。对于所有肽而言，每50微米切片中IR神经元的平均数量通常在胸段脊髓中最低，在下腰段/骶段脊髓中最高。对于脑啡肽和强啡肽，每个节段IR神经元的估计总数以及每体积（mm3）IR神经元的数量通常在中腰段最低，在胸段和下腰段/骶段脊髓中最高。对于神经降压素，每个节段神经元的估计总数在胸段仍然最低，在下腰段/骶段最高。每体积神经降压素IR神经元的数量在胸段和中腰段脊髓中相等，但在下腰段/骶段水平仍然最高。本研究中量化的IR神经元可能是中间神经元，也可能作为脊髓上投射神经元。在接受相对大量内脏传入输入的节段中观察到大量IR神经元，这表明其中一些神经元可能参与内脏感觉处理。此外，IR神经元的节段分布表明，关于阿片类和/或神经降压素肽作用的生理学和药理学研究应根据所研究的脊髓节段来解释。
