Smith K J, Kodama R T, Liuzzi F J
Department of Anatomy and Neurobiology, Eastern Virginia Medical School, Norfolk 23501.
Brain Res. 1992 Mar 13;575(1):79-85. doi: 10.1016/0006-8993(92)90426-a.
The demonstration that some central nervous system (CNS) axons can regenerate when provided with a suitable environment raises the possibility of new treatments for CNS injury. However, at present the conditions for optimal regeneration are not well understood. For example, the methods used in previous studies have entailed CNS trauma as part of the research protocol (e.g. that resulting from the implantation of peripheral nerve grafts), and so the role of neuronal or axonal injury in the regrowth observed has been difficult to establish. To determine whether such injury is necessary for the central reinnervation of denervated peripheral nerve, the L5 dorsal root has been chronically denervated in rats by freeze-thawing its dorsal root ganglion (DRG), and the root has been left attached to either traumatized or non-traumatized spinal cord. The trauma induced was quite mild, and resulted from several vertical insertions of a fine needle. Two to 4 months later, retrogradely transported horseradish peroxidase (HRP) was used to label spinal neurons which sent axons into the denervated roots. HRP-labelled neurons were found in each of the spinal cords subjected to trauma, but no labelled neurons were observed in any of the non-traumatized cords. The number of HRP-labelled neurons in individual spinal cords was positively correlated with the degree of spinal cord trauma. We conclude first that the chronic and intimate presence of a denervated PNS tissue in continuity with the spinal cord is not, in itself, a sufficient stimulus to induce its reinnervation by CNS axons. Second, we conclude that under the conditions of this experiment CNS trauma is a prerequisite for the reinnervation of denervated peripheral nervous tissue by CNS axons.
有证据表明，一些中枢神经系统（CNS）轴突在具备合适环境时能够再生，这为中枢神经系统损伤的新治疗方法带来了可能性。然而，目前对于最佳再生条件的了解还不够深入。例如，先前研究中所使用的方法将中枢神经系统创伤作为研究方案的一部分（例如，因植入周围神经移植物而导致的创伤），因此，在观察到的轴突再生中，神经元或轴突损伤所起的作用难以确定。为了确定这种损伤对于失神经支配的周围神经的中枢再支配是否必要，通过对大鼠L5背根神经节进行冻融处理，使其L5背根长期失神经支配，并将该背根与受创伤或未受创伤的脊髓相连。所诱导的创伤相当轻微，是由一根细针多次垂直插入造成的。2至4个月后，使用逆行运输的辣根过氧化物酶（HRP）标记那些将轴突发送到失神经支配的背根中的脊髓神经元。在遭受创伤的每一条脊髓中都发现了HRP标记的神经元，但在任何未受创伤的脊髓中均未观察到标记的神经元。各个脊髓中HRP标记神经元的数量与脊髓创伤程度呈正相关。我们首先得出结论，与脊髓连续的失神经支配的周围神经组织的长期紧密存在本身并不足以刺激中枢神经系统轴突对其进行再支配。其次，我们得出结论，在本实验条件下，中枢神经系统创伤是中枢神经系统轴突对失神经支配的周围神经组织进行再支配的先决条件。
