Kwiat G C, Basbaum A I
Keck Center for Integrative Neuroscience, University of California, San Francisco 94143.
Somatosens Mot Res. 1992;9(2):157-73. doi: 10.3109/08990229209144768.
Although it has been proposed that the locus coeruleus is the predominant, if not exclusive, brainstem origin of the noradrenergic innervation of the spinal dorsal horn, pharmacological studies argue otherwise. In this study we made localized injections of the retrograde tracer wheatgerm agglutinin conjugated to apo-horseradish peroxidase gold (WGA:apoHRP-Au), in conjunction with immunocytochemical labeling for tyrosine hydroxylase (TH) or serotonin (5-HT), to identify the brainstem source of the noradrenaline (NA) and 5-HT innervation of the dorsal horn of the rat. Our studies were concentrated in the C5 spinal segment. The pattern of labeling was only studied in animals in which the tracer injection was restricted to the dorsal horn. In these rats, TH-immunoreactive neurons in widespread regions of the brainstem, including the locus coeruleus, subcoeruleus, A5, and A7 cell groups, were found to project to the dorsal horn. In terms of absolute numbers of double-labeled cells, no one noradrenergic cell group predominated. As expected, dorsal-horn-projecting 5-HT-immunoreactive neurons were found within the 5-HT populations of the rostroventromedial medulla and caudal pons, including the nucleus raphe magnus, nucleus paragigantocellularis (PGi), and ventral portions of the nucleus gigantocellularis (Gi). The majority of retrogradely labeled 5-HT-immunoreactive cells were, however, located off the midline, in the ipsilateral PGi and ventral Gi. Finally, a large number of retrogradely labeled, non-5-HT cells were found intermingled among the 5-HT cells of this region. Our results provide evidence that the noradrenergic regulation of nociceptive transmission at the spinal cord level arises from direct spinal projections of several brainstem noradrenergic cell groups.
尽管有人提出蓝斑是脊髓背角去甲肾上腺素能神经支配的主要（如果不是唯一的）脑干起源，但药理学研究却提出了不同观点。在本研究中，我们进行了局部注射与脱辅基辣根过氧化物酶金结合的逆行示踪剂小麦胚芽凝集素（WGA:apoHRP-Au），并结合酪氨酸羟化酶（TH）或5-羟色胺（5-HT）的免疫细胞化学标记，以确定大鼠背角去甲肾上腺素（NA）和5-HT神经支配的脑干来源。我们的研究集中在C5脊髓节段。仅在示踪剂注射局限于背角的动物中研究标记模式。在这些大鼠中，发现脑干广泛区域（包括蓝斑、蓝斑下、A5和A7细胞群）的TH免疫反应性神经元投射到背角。就双标细胞的绝对数量而言，没有一个去甲肾上腺素能细胞群占主导。正如预期的那样，在延髓吻侧腹内侧和脑桥尾侧的5-HT群体中，包括中缝大核、巨细胞旁核（PGi）和巨细胞大核（Gi）的腹侧部分，发现了投射到背角的5-HT免疫反应性神经元。然而，大多数逆行标记的5-HT免疫反应性细胞位于中线以外，在同侧PGi和Gi腹侧。最后，在该区域的5-HT细胞中发现大量逆行标记的非5-HT细胞。我们的结果提供了证据，表明脊髓水平伤害性传递的去甲肾上腺素能调节源自几个脑干去甲肾上腺素能细胞群的直接脊髓投射。
