Axon Regenration: Synergistic Actions of the MAPK and Cyclic AMP Pathways

描述（由申请人提供）：我们的最终目标是开发有效的策略，以改善人类脊髓损伤（SCI）后的结果。 我们已经证明了（Pearse等人，2004），SC植入物、将cAMP一次性注射到植入物上方和下方的脊髓中、以及两周皮下输注咯利普兰的三重组合诱导了多巴胺能纤维大量生长到植入物中，并进一步生长到植入物尾侧的脊髓中。 在尾索中轴突生长最好的组中观察到运动测试分数的显著改善。 为了建立在这些结果的基础上，我们提出了使用相同的损伤模型和SC移植的三个特定目的（Pearse等人，2004年）。 在目标1中，我们将确定cAMP升高的最有效递送部位（病变、中缝胞体或两者）（通过测量纤维和评估运动）。 已知BDNF还促进神经元能轴突生长到SC移植物尾侧的脊髓中;因此，我们将使用相同的SCI范例来确定BDNF递送的最有效部位。 在目标2中，我们建议测试cAMP升高和BDNF给药的组合比单独使用任何一种更有效的可能性。 将cAMP（最佳途径）和BDNF（最佳途径）的施用组合，并将肾上腺素能轴突生长反应与单独使用任一因子观察到的反应进行比较。 行为测试结果将与每只动物的轴突生长相关。 在目标3中，我们建议在我们最有效的治疗后确定多巴胺能投射的功能。 首先，将评估由β受体阻断剂引起的运动变化。 其次，我们将确定反射反应的躯体传入刺激后，电刺激中缝脊神经通路。 第三，验证最佳处理后下行纤维释放5-HT的情况。 探索联合疗法以改善损伤部位以外的肾上腺素能纤维生长，并确定潜在改善的生长对运动的作用，将在未来产生新的临床策略。

DESCRIPTION (provided by applicant): Our ultimate goal is to develop effective strategies to improve outcome after human spinal cord injury (SCI). We have demonstrated (Pearse et al., 2004) that a triple combination of a SC implant, a one-time injection of cAMP into the cord above and below the implant, and a two-week subcutaneous infusion of Rolipram induced substantial growth of serotonergic fibers into the implant and beyond into the cord caudal to the implant. A marked improvement in locomotor test scores was observed in groups with the best growth of serotonergic axons in the caudal cord. To build on these results, we propose three Specific Aims using the same injury model and SC grafting (Pearse et al., 2004). In Aim 1, we will determine the most effective delivery site (lesion, raphe somata, or both) for cAMP elevation (by measuring fibers and evaluating locomotion). BDNF is known also to promote growth of serotonergic axons into the cord caudal to a SC graft; therefore we will determine the most efficacious site for BDNF delivery using the same SCI paradigm. In Aim 2, we propose to test the possibility that the combination of cAMP elevation and BDNF administration will be more effective than either one alone. Administration of cAMP (best route) and BDNF (best route) will be combined and the serotonergic axon growth response compared to that observed with either factor alone. Behavioral test results will be correlated with axon growth in each animal. In Aim 3, we propose to determine the functionality of the serotonergic projections after our most effective treatment. First, changes in locomotion caused by pharmacologically blocking serotonergic receptors will be assessed. Second, we will determine reflex responses to somatic afferent stimulation following electrical stimulation of raphespinal pathways. Third, the release of 5-HT by descending fibers after the best treatment will be verified. Exploration of combined therapies to improve serotonergic fiber growth beyond the site of injury and determination of the role of the potentially improved growth on locomotion will lead to new clinical strategies in the future.