Ohara S, Roth K A, Beaudet L N, Schmidt R E
Department of Neurology, Washington University School of Medicine, St. Louis, Missouri 63110.
J Neuropathol Exp Neurol. 1994 Nov;53(6):646-62. doi: 10.1097/00005072-199411000-00012.
Gracile neuroaxonal dystrophy (NAD) is a hallmark of the aging human and rodent sensory nervous systems which may represent an abnormal transganglionic response to peripheral axonal injury. To examine the structural plasticity of central dorsal root ganglia (DRG)-derived axons in the gracile nucleus, we evaluated the response of the lumbar DRG and their central projections to sciatic nerve injury in young and old rats. In uninjured rats neither the DRG nor its central projections contained histochemical immunoreactivity for neuropeptide Y (NPY). However, within 1 week of sciatic nerve crush or transection injury, NPY immunoreactivity appeared in the lumbar DRG and its central projections, reaching an apparent maximum in number and intensity of processes at 28 days. Neuropeptide Y immunoreactivity was more intense and sustained in response to transection compared to crush injury, results supported by NPY radioimmunoassay. Neuropeptide Y-immunoreactive processes in the gracile nuclei of axotomized young animals consisted of delicate axons or slightly enlarged profiles that may represent regenerative elements. Lumbar dorsal rhizotomy performed simultaneously with sciatic nerve transection prevented the transganglionic NPY response. Dystrophic axons in the gracile nucleus of non-lesioned aged animals were not NPY-immunoreactive; however, after sciatic nerve transection, NPY immunoreactivity developed in both delicate axons and markedly swollen dystrophic elements, a finding confirmed by ultrastructural immunolocalization. These results establish that despite the presence of NAD in DRG projections to aged gracile nuclei these elements remain capable of a plastic NPY response to peripheral nerve injury.
薄束神经轴索性营养不良（NAD）是人类和啮齿动物衰老感觉神经系统的一个特征，可能代表对周围轴突损伤的一种异常跨神经节反应。为了研究薄束核中源自中枢背根神经节（DRG）的轴突的结构可塑性，我们评估了年轻和老年大鼠腰段DRG及其中枢投射对坐骨神经损伤的反应。在未受伤的大鼠中，DRG及其中枢投射均未检测到神经肽Y（NPY）的组织化学免疫反应性。然而，在坐骨神经挤压或横断损伤后1周内，NPY免疫反应性出现在腰段DRG及其中枢投射中，在28天时其突起的数量和强度达到明显最大值。与挤压损伤相比，横断损伤后神经肽Y免疫反应性更强且持续时间更长，NPY放射免疫测定结果支持了这一结果。轴突切断的年轻动物薄束核中神经肽Y免疫反应性突起由纤细的轴突或略有增大的轮廓组成，可能代表再生成分。与坐骨神经横断同时进行的腰段背根切断术可防止跨神经节的NPY反应。未损伤的老年动物薄束核中的营养不良轴突无NPY免疫反应性；然而，坐骨神经横断后，纤细轴突和明显肿胀的营养不良成分中均出现了NPY免疫反应性，超微结构免疫定位证实了这一发现。这些结果表明，尽管在投射到老年薄束核的DRG中存在NAD，但这些成分仍能够对外周神经损伤产生可塑性的NPY反应。
