Lindå H, Piehl F, Dagerlind A, Verge V M, Arvidsson U, Cullheim S, Risling M, Ulfhake B, Hökfelt T
Department of Anatomy, Karolinska Institutet, Stockholm, Sweden.
Exp Brain Res. 1992;91(2):284-95. doi: 10.1007/BF00231661.
In situ hybridization histochemistry was used to detect cell bodies expressing mRNA encoding for the phosphoprotein GAP-43 in the lumbosacral spinal cord of the adult rat, cat and monkey under normal conditions and, in the cat and rat, also after different types of lesions. In the normal spinal cord, a large number of neurons throughout the spinal cord gray matter were found to express GAP-43 mRNA. All neurons, both large and small, in the motor nucleus (Rexed's lamina IX) appeared labeled, indicating that both alpha and gamma motoneurons express GAP-43 mRNA under normal conditions. After axotomy by an incision in the ventral funiculus or a transection of ventral roots or peripheral nerves, GAP-43 mRNA was clearly upregulated in axotomized motoneurons, including both alpha and gamma motoneurons. An increase in GAP-43 mRNA expression was already detectable 24 h postoperatively in lumbar motoneurons both after a transection of the sciatic nerve at knee level and after a transection of ventral roots. At this time, a stronger response was seen in the motoneurons which had been subjected to the distal sciatic nerve transection than was apparent for the more proximal ventral root lesion. An upregulation of GAP-43 mRNA could also be found in intact motoneurons located on the side contralateral to the lesion, but only after a peripheral nerve transection, indicating that the concomitant influence of dorsal root afferents may play a role in GAP-43 mRNA regulation. However, a dorsal root transection alone did not seem to have any detectable influence on the expression of GAP-43 mRNA in spinal motoneurons, while the neurons located in the superficial laminae of the dorsal horn responded with an upregulation of GAP-43 mRNA. The presence of high levels of GAP-43 in neurons has been correlated with periods of axonal growth during both development and regeneration. The role for GAP-43 in neurons under normal conditions is not clear, but it may be linked with events underlying remodelling of synaptic relationships or transmitter release. Our findings provide an anatomical substrate to support such a hypothesis in the normal spinal cord, and indicate a potential role for GAP-43 in axon regeneration of the motoneurons, since GAP-43 mRNA levels was strongly upregulated following both peripheral axotomy and axotomy within the spinal cord.(ABSTRACT TRUNCATED AT 400 WORDS)
采用原位杂交组织化学方法，在正常条件下检测成年大鼠、猫和猴腰骶部脊髓中表达磷蛋白GAP - 43编码mRNA的细胞体，并且在猫和大鼠中，还检测了不同类型损伤后的情况。在正常脊髓中，发现脊髓灰质中大量神经元表达GAP - 43 mRNA。运动核（Rexed板层IX）中的所有神经元，无论大小，均显示出标记，这表明在正常条件下α和γ运动神经元均表达GAP - 43 mRNA。在腹侧索切开、腹根横断或外周神经横断进行轴突切断术后，轴突切断的运动神经元（包括α和γ运动神经元）中GAP - 43 mRNA明显上调。在膝水平切断坐骨神经和切断腹根后，术后24小时在腰运动神经元中即可检测到GAP - 43 mRNA表达增加。此时，坐骨神经远端横断的运动神经元比腹根近端损伤的运动神经元反应更强。在损伤对侧完整的运动神经元中也可发现GAP - 43 mRNA上调，但仅在周围神经横断后出现，这表明背根传入神经的伴随影响可能在GAP - 43 mRNA调节中起作用。然而，单独切断背根似乎对脊髓运动神经元中GAP - 43 mRNA的表达没有任何可检测到的影响，而背角浅层的神经元则表现为GAP - 43 mRNA上调。神经元中高水平GAP - 43的存在与发育和再生过程中的轴突生长时期相关。正常条件下GAP - 43在神经元中的作用尚不清楚，但它可能与突触关系重塑或递质释放的潜在事件有关。我们的研究结果为在正常脊髓中支持这一假设提供了解剖学基础，并表明GAP - 43在运动神经元轴突再生中具有潜在作用，因为在周围轴突切断和脊髓内轴突切断后，GAP - 43 mRNA水平均强烈上调。（摘要截选至400字）
