Ma W, Bisby M A
Department of Physiology, Queen's University, Kingston, Ontario, Canada.
Neuroscience. 1998 Oct;86(4):1217-34. doi: 10.1016/s0306-4522(98)00068-2.
Partial nerve injury is more likely to cause neuropathic pain than complete nerve injury. We have compared the changes in neuropeptide expression in primary sensory neurons which follow complete and partial injuries to determine if these might be involved. Since more neurons are damaged by complete injury, we expected that complete sciatic nerve injury would simply cause greater increases in neuropeptide Y and vasoactive intestinal peptide than partial injury. We examined neuropeptide Y and vasoactive intestinal peptide immunoreactivities in L4 and L5 dorsal root ganglia, the dorsal horn of L4-L5 spinal cord, and the gracile nuclei of rats killed 14 days after unilateral complete sciatic nerve transection, partial sciatic nerve transection and chronic constriction injury of the sciatic nerves. In all three groups of rats, neuropeptide Y- and vasoactive intestinal peptide-immunoreactive neurons were increased in the ipsilateral L4 and L5 dorsal root ganglion when compared with the contralateral side. Most neuropeptide Y-immunoreactive neurons were of medium and large size, but a few were small. Neuropeptide Y-immunoreactive axonal fibers were increased from laminae I to IV, and vasoactive intestinal peptide-immunoreactive axonal fibers were increased in laminae I and II, of the ipsilateral dorsal horn of L4-L5 spinal cord. The increases of neuropeptide Y and vasoactive intestinal peptide immunoreactivities in the dorsal horn were similar among the three groups. However, only after constriction injury were some vasoactive intestinal peptide-immunoreactive neurons seen in the deeper laminae of the ipsilateral dorsal horn. Robust neuropeptide Y-immunoreactive axonal fibers and some neuropeptide Y-immunoreactive cells were seen in the ipsilateral gracile nuclei of all three groups of animals, but neuropeptide Y-immunoreactive cells were more prominent after constriction injury. Contrary to our expectations, partial and complete sciatic nerve injuries induced similar increases in neuropeptide Y and vasoactive intestinal peptide in lumbar dorsal root ganglion neurons and their central projections in the dorsal horn and the gracile nuclei two weeks after injury. Some neurons whose axons were spared by partial injury may also increase neuropeptide Y or vasoactive intestinal peptide expression. Altered neuropeptide release from these functional sensory neurons may play a role in neuropathic pain.
与完全性神经损伤相比，部分性神经损伤更易引发神经性疼痛。我们比较了完全性和部分性损伤后初级感觉神经元中神经肽表达的变化，以确定这些变化是否与之有关。由于完全性损伤会损伤更多神经元，我们预计完全性坐骨神经损伤会比部分性损伤更显著地增加神经肽Y和血管活性肠肽的表达。我们检测了单侧完全性坐骨神经横断、部分性坐骨神经横断以及坐骨神经慢性压迫损伤后14天处死的大鼠L4和L5背根神经节、L4 - L5脊髓背角以及薄束核中神经肽Y和血管活性肠肽的免疫反应性。在所有三组大鼠中，与对侧相比，同侧L4和L5背根神经节中神经肽Y和血管活性肠肽免疫反应性神经元均增加。大多数神经肽Y免疫反应性神经元为中等大小和大尺寸，但也有少数为小尺寸。L4 - L5脊髓同侧背角中，神经肽Y免疫反应性轴突纤维从I层到IV层增加，血管活性肠肽免疫反应性轴突纤维在I层和II层增加。三组中背角神经肽Y和血管活性肠肽免疫反应性的增加相似。然而，仅在压迫损伤后，同侧背角深层才可见一些血管活性肠肽免疫反应性神经元。在所有三组动物的同侧薄束核中均可见到粗壮的神经肽Y免疫反应性轴突纤维和一些神经肽Y免疫反应性细胞，但在压迫损伤后神经肽Y免疫反应性细胞更为突出。与我们的预期相反，损伤两周后，部分性和完全性坐骨神经损伤在腰背根神经节神经元及其在背角和薄束核中的中枢投射中诱导神经肽Y和血管活性肠肽出现相似的增加。一些轴突未受部分性损伤影响的神经元也可能增加神经肽Y或血管活性肠肽的表达。这些功能性感觉神经元神经肽释放的改变可能在神经性疼痛中起作用。
