Wang S D, Goldberger M E, Murray M
Department of Anatomy, Medical College of Pennsylvania, Philadelphia 19129.
J Comp Neurol. 1991 Feb 22;304(4):555-68. doi: 10.1002/cne.903040405.
Plasticity of spinal systems in response to lumbosacral deafferentation has previously been described for the cat, by using immunocytochemistry to demonstrate plasticity of tachykinin systems and degeneration methods to demonstrate plasticity of descending systems. In this study, we describe the response to lumbosacral deafferentation in the adult rat. Application of immunocytochemical methods to visualize tachykinins (predominantly substance P magnitude of SP), serotonin (5-HT), and dopamine B-hydroxylase (DBH), the synthesizing enzyme for norepinephrine, permits us to compare the response of SP systems in rat and cat spinal cord and to examine the response of two descending systems, serotoninergic and noradrenergic, to deafferentation. We used image analysis of light microscopic preparations to quantify the immunoreaction product in the spinal cord in order to estimate the magnitude, time course and localization of changes induced by the lesion. The distribution of SP, serotoninergic (5-HT), and noradrenergic staining in the spinal cord of rat is very similar to that of the cat. Unilateral lumbosacral rhizotomy elicits a partial depletion, followed by a partial replacement of tachykinin immunoreactivity in laminae I and II. This response was similar to that described for the cat, although characterized by a longer time course, and, as in the cat, is likely due to plasticity of tachykinin containing interneurons. The same lesion elicits no depletion but a marked and permanent increase in 5-HT immunoreactivity in laminae I and II, which develops more rapidly than the response by the SP system. These results indicate sprouting or increased production of SP and 5-HT in response to deafferentation. No change was seen in DBH immunoreactivity, indicating that the noradrenergic system does not show plasticity in response to deafferentation. Our results demonstrate that dorsal rhizotomy evokes different effects in different systems in the adult spinal cord of the rat and thus suggests that the response of undamaged pathways to partial denervation of their target is regulated rather than random.
先前已通过免疫细胞化学方法证明速激肽系统的可塑性，并采用变性方法证明下行系统的可塑性，对猫腰骶去传入后脊髓系统的可塑性进行了描述。在本研究中，我们描述了成年大鼠对腰骶去传入的反应。应用免疫细胞化学方法来可视化速激肽（主要是P物质，即SP）、5-羟色胺（5-HT）和多巴胺β-羟化酶（DBH，去甲肾上腺素的合成酶），使我们能够比较大鼠和猫脊髓中SP系统的反应，并研究两个下行系统，即5-羟色胺能和去甲肾上腺素能系统对去传入的反应。我们使用光学显微镜制剂的图像分析来量化脊髓中的免疫反应产物，以估计损伤引起的变化的程度、时间进程和定位。大鼠脊髓中SP、5-羟色胺能（5-HT）和去甲肾上腺素能染色的分布与猫非常相似。单侧腰骶神经根切断术会引起I层和II层中速激肽免疫反应性的部分耗竭，随后是部分替代。这种反应与猫的情况相似，尽管其特征是时间进程更长，并且与猫一样，可能是由于含速激肽的中间神经元的可塑性所致。相同的损伤不会引起耗竭，但会导致I层和II层中5-HT免疫反应性显著且永久性增加，其发展速度比SP系统的反应更快。这些结果表明，去传入后会出现SP和5-HT的发芽或产生增加。DBH免疫反应性未见变化，表明去甲肾上腺素能系统对去传入不显示可塑性。我们的结果表明，背根切断术在成年大鼠脊髓的不同系统中引发不同的效应，因此表明未受损通路对其靶标的部分去神经支配的反应是受调节的，而非随机的。
