Clark F M, Proudfit H K
Department of Pharmacology, University of Illinois, Chicago 60680.
Brain Res. 1992 Sep 18;591(1):44-53. doi: 10.1016/0006-8993(92)90976-g.
Pontospinal noradrenergic neurons located in the A5, A6 (locus coeruleus, LC), and A7 cell groups are the major source of the noradrenergic innervation of the spinal cord. We have recently examined the specific terminations of these three cell groups in the spinal cord and found that the LC provides the major noradrenergic innervation of the ventral horn, while the A7 and A5 cell groups innervate the dorsal horn and intermediate zone, respectively. However, the results of similar experiments from another laboratory have shown that noradrenergic neurons in the locus coeruleus primarily innervate the dorsal horn, while the A5 and A7 innervate the intermediate zone and the ventral horn. These conflicting results may be due to fundamental genetic differences between the rats used in our experiments (Sasco Sprague-Dawley) and those used by the other laboratory (Harlan Sprague-Dawley). This possibility was examined by determining the projections of coeruleospinal neurons in these two rat substrains using the anterograde tracer Phaseolus vulgaris leucoagglutinin. The results indicate that in Sasco rats the LC neurons project through the ipsilateral ventromedial funiculus and terminate almost exclusively in the medial part of laminae VII and VIII, the motoneuron pool of lamina IX, and lamina X. In contrast, LC neurons in Harlan rats project bilaterally through the superficial dorsal horn and the dorsolateral funiculus and terminate most heavily in dorsal horn laminae I-IV. In addition, the LC neurons of Sasco rats innervate cervical spinal cord segments more densely than lumbar spinal cord segments, while in Harlan rats the lumbar spinal cord is more densely innervated than the cervical spinal cord. These results indicate that the projections of coeruleospinal neurons in Sasco rats are fundamentally different from those in Harlan rats and suggest that noradrenergic LC neurons may have different physiological functions in these two rat substrains.
位于A5、A6（蓝斑，LC）和A7细胞群的脑桥脊髓去甲肾上腺素能神经元是脊髓去甲肾上腺素能神经支配的主要来源。我们最近研究了这三个细胞群在脊髓中的特定终末，发现蓝斑为腹角提供主要的去甲肾上腺素能神经支配，而A7和A5细胞群分别支配背角和中间带。然而，另一个实验室的类似实验结果表明，蓝斑中的去甲肾上腺素能神经元主要支配背角，而A5和A7支配中间带和腹角。这些相互矛盾的结果可能是由于我们实验中使用的大鼠（Sasco Sprague-Dawley）与另一个实验室使用的大鼠（Harlan Sprague-Dawley）之间存在根本的基因差异。通过使用顺行示踪剂菜豆白细胞凝集素确定这两个大鼠亚系中蓝斑脊髓神经元的投射来检验这种可能性。结果表明，在Sasco大鼠中，蓝斑神经元通过同侧腹内侧索投射，几乎仅终止于VII层和VIII层的内侧部分、IX层的运动神经元池和X层。相比之下，Harlan大鼠中的蓝斑神经元通过浅背角和背外侧索双侧投射，在背角I-IV层的终末最为密集。此外，Sasco大鼠的蓝斑神经元对颈段脊髓节段的支配比腰段脊髓节段更密集，而在Harlan大鼠中，腰段脊髓的神经支配比颈段脊髓更密集。这些结果表明，Sasco大鼠中蓝斑脊髓神经元的投射与Harlan大鼠中的投射有根本不同，并表明去甲肾上腺素能蓝斑神经元在这两个大鼠亚系中可能具有不同的生理功能。
