Blessing W W, Li Y W, Wesselingh S L
Department of Medicine, Flinders University of South Australia, Bedford Park.
Neuroscience. 1991;42(1):261-74. doi: 10.1016/0306-4522(91)90163-i.
The recent introduction of live viruses as intra-axonal tracing agents has raised questions concerning which central neurons are transneuronally labelled after application of the virus to peripheral organs or peripheral nerves. Since the central connections of the vagus nerve have been well described using conventional neuronal tracing agents, we chose to inject Herpes Simplex Virus Type 1 into the cervical vagus of the rat. After survival times of up to 3 days the rat brains were processed immunohistochemically using a polyclonal antiserum against herpes simplex virus. Two days after injection of the virus we observed viral antigen in the area postrema and in the nucleus tractus solitarius and the dorsal motor nucleus of the vagus (dorsal vagal complex), principally ipsilaterally. At this survival time the viral antigen in the dorsal vagal complex was largely confined to glial cells. After 3 days the viral antigen was localized both in glia and in nerve cells within the dorsal vagal complex and in brain regions previously demonstrated, using conventional tracing procedures, to contain neurons with axonal projections to the dorsal vagal complex. This was true for medullary, pontine, midbrain and hypothalamic regions and for telencephalic regions including the amygdala, the bed nucleus of the stria terminalis, and the insular and medial frontal cortices. Many of the nerve cells containing viral antigen were displayed in a Golgi-like manner, with excellent visualization of the dendritic tree. Axonal processes, in contrast, were not visualized. We used co-localization studies to confirm previous findings concerning monoamine neurotransmitter-related antigens present in medullary and pontine neurons projecting to the dorsal vagal complex. After 3 days there were many Herpes Simplex Virus Type 1-containing glial cells along the intra-medullary course of the vagal rootlets. However, no viral antigen was found in brain regions containing neurons whose axons pass through the region of glial cell-labelled rootlets. Glial cells containing viral antigen were particularly numerous in brain regions known to receive an input from neurons in the area postrema and the dorsal vagal complex. Taken together with our observation concerning the early appearance of viral antigen within glial cells in the dorsal vagal complex, this suggests that when the virus reaches the axon terminal portion it is transferred to nearby glial cells and possibly enters central neurons by way of these structures.
最近将活病毒用作轴突内示踪剂引发了一些问题，即当病毒应用于外周器官或外周神经后，哪些中枢神经元会被跨神经元标记。由于迷走神经的中枢连接已使用传统的神经元示踪剂得到了很好的描述，我们选择将1型单纯疱疹病毒注射到大鼠的颈迷走神经中。在长达3天的存活时间后，使用针对单纯疱疹病毒的多克隆抗血清对大鼠脑进行免疫组织化学处理。注射病毒两天后，我们在最后区、孤束核和迷走神经背运动核（迷走背复合体）中观察到病毒抗原，主要在同侧。在这个存活时间，迷走背复合体中的病毒抗原主要局限于神经胶质细胞。3天后，病毒抗原定位在迷走背复合体中的神经胶质细胞和神经细胞中，以及先前使用传统示踪程序证明含有向迷走背复合体投射轴突的神经元的脑区中。延髓、脑桥、中脑和下丘脑区域以及端脑区域，包括杏仁核、终纹床核、岛叶和内侧额叶皮质都是如此。许多含有病毒抗原的神经细胞以类似高尔基染色的方式显示，树突树可视化良好。相比之下，轴突过程未被可视化。我们使用共定位研究来证实先前关于投射到迷走背复合体的延髓和脑桥神经元中存在单胺神经递质相关抗原的发现。3天后，沿着迷走神经根的髓内行程有许多含有1型单纯疱疹病毒的神经胶质细胞。然而，在含有轴突穿过神经胶质细胞标记的根区域的神经元的脑区中未发现病毒抗原。在已知接受最后区和迷走背复合体神经元输入的脑区中，含有病毒抗原的神经胶质细胞特别多。结合我们关于迷走背复合体中神经胶质细胞内病毒抗原早期出现的观察结果，这表明当病毒到达轴突终末部分时，它会转移到附近的神经胶质细胞，并可能通过这些结构进入中枢神经元。
