Grzanna R, Chee W K, Akeyson E W
Department of Neuroscience, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.
J Comp Neurol. 1987 Sep 1;263(1):76-91. doi: 10.1002/cne.902630107.
Retrograde transport of the fluorescent tracer True Blue was used in combination with immunohistochemical staining of dopamine-beta-hydroxylase (a marker protein for noradrenergic neurons) to determine the origin of noradrenergic projections to three cranial nerve nuclei: 1) the motor nucleus of the trigeminal nerve, 2) the motor nucleus of the facial nerve, and 3) the spinal trigeminal nucleus pars interpolaris. Noradrenergic cells in the rat brainstem were divided into subgroups and their numbers were determined in serial sections stained with an antiserum to rat dopamine-beta-hydroxylase. Following tracer injections into the three brainstem nuclei, retrogradely labeled noradrenergic neurons were counted and the percentage of True Blue-labeled noradrenergic cells in each subgroup was calculated. Injections of tracer into the three cranial nerve nuclei resulted in distinctly different labeling patterns of noradrenergic cells. Of the total number of norepinephrine neurons projecting to the motor nucleus of the trigeminal nerve, 68% were observed within the A7 cell group; 75% of those innervating the motor nucleus of the facial nerve were found in the A5 cell group, and 65% of those projecting to the spinal trigeminal nucleus pars interpolaris were present in the locus ceruleus and subceruleus. These findings indicate that norepinephrine cells in the rat brainstem do not constitute a homogeneous population of cells but that several discrete systems can be identified that differ not only in topography but also in the terminal distribution of their axons. This combined retrograde transport-immunohistochemical study reveals a much higher degree of topographic order in the projections of norepinephrine neurons than has previously been recognized. The observation of differential projections of noradrenergic subgroups argues against the notion of a global influence of these cells over functionally diverse areas of the brainstem.
荧光示踪剂真蓝的逆行运输与多巴胺-β-羟化酶（去甲肾上腺素能神经元的标记蛋白）的免疫组织化学染色相结合，以确定投射到三个脑神经核的去甲肾上腺素能投射的起源：1）三叉神经运动核，2）面神经运动核，3）三叉神经脊髓束核极间部。大鼠脑干中的去甲肾上腺素能细胞被分为亚组，并在使用抗大鼠多巴胺-β-羟化酶血清染色的连续切片中确定其数量。在将示踪剂注射到三个脑干核之后，对逆行标记的去甲肾上腺素能神经元进行计数，并计算每个亚组中真蓝标记的去甲肾上腺素能细胞的百分比。向三个脑神经核注射示踪剂导致去甲肾上腺素能细胞的标记模式明显不同。投射到三叉神经运动核的去甲肾上腺素能神经元总数中，68%见于A7细胞群；支配面神经运动核的神经元中，75%见于A5细胞群，而投射到三叉神经脊髓束核极间部的神经元中，65%见于蓝斑和蓝斑下核。这些发现表明，大鼠脑干中的去甲肾上腺素能细胞并非由同质细胞组成，而是可以识别出几个离散的系统，它们不仅在拓扑结构上不同，而且在轴突的终末分布上也不同。这种逆行运输与免疫组织化学相结合的研究揭示，去甲肾上腺素能神经元投射的拓扑顺序程度比以前认识到的要高得多。去甲肾上腺素能亚组的差异投射观察结果与这些细胞对脑干功能多样区域具有全局影响的观点相悖。
