Chung K, Chung J M
Marine Biomedical Institute, University of Texas Medical Branch, 301 University Boulevard, Galveston, TX 77555-1069, USA.
Brain Res. 2001 Mar 23;895(1-2):204-12. doi: 10.1016/s0006-8993(01)02092-3.
It is well documented that there is an increase in the number of sympathetic fibers within the dorsal root ganglion (DRG) after a peripheral nerve injury. The present study examined the numbers and distribution of sympathetic fibers in the DRG and their sprouting routes by utilizing various surgical manipulations and retrograde tracing and immunohistochemical staining methods in spinal nerve-ligated neuropathic rats. The appearance of many double immunostained fibers with antibodies to tyrosine hydroxylase (TH) and growth associated protein-43 (GAP-43) in the L5 DRG 1 week after L5 spinal nerve ligation, indicated sprouting of sympathetic fibers. The confined location of early sprouting sympathetic fibers in the distal half of the L5 DRG confirmed that sprouting fibers come primarily from the injured spinal nerve. A second cut proximal to the previously ligated L5 spinal nerve -- a process which would transect the regenerating sympathetic fibers extending from the injury site -- did not change the density of sympathetic fibers in the L5 DRG. When retrograde tracers (fast blue and diamidino yellow) were injected into the L5 spinal nerve and DRG, respectively, the number of double-labeled sympathetic postganglionic neurons was greatly increased after spinal nerve ligation, suggesting the increased number of sympathetic neurons projecting to both the spinal nerve and DRG. All these results indicate that many sympathetic fibers in the DRG are regenerating branches that are sprouting from the proximal part of the injured spinal nerve (regenerative collateral sprouting).
有充分的文献记载，周围神经损伤后背根神经节（DRG）内的交感神经纤维数量会增加。本研究通过在脊髓神经结扎的神经性大鼠中运用各种手术操作、逆行追踪和免疫组织化学染色方法，研究了DRG中交感神经纤维的数量、分布及其发芽途径。L5脊髓神经结扎1周后，L5 DRG中出现许多用酪氨酸羟化酶（TH）和生长相关蛋白-43（GAP-43）抗体进行双重免疫染色的纤维，表明交感神经纤维发芽。早期发芽的交感神经纤维在L5 DRG远端一半的局限位置证实，发芽纤维主要来自受伤的脊髓神经。在先前结扎的L5脊髓神经近端进行第二次切断——这一过程会横断从损伤部位延伸的再生交感神经纤维——并没有改变L5 DRG中交感神经纤维的密度。当分别将逆行示踪剂（快蓝和双脒基黄）注入L5脊髓神经和DRG时，脊髓神经结扎后双重标记的交感神经节后神经元数量大大增加，表明投射到脊髓神经和DRG的交感神经元数量增加。所有这些结果表明，DRG中的许多交感神经纤维是从受伤脊髓神经近端发芽的再生分支（再生侧支发芽）。
