Adaptive rewiring of the mature brain after injury

描述（由申请人提供）：中风或创伤性脑损伤的恢复部分受到成熟神经元无法显著重组其连接的限制。这种重组可能需要积极的刺激来激活神经元的内在生长状态，并需要克服通常抑制生长的抑制信号的方法。肌苷，一种嘌呤核苷，激活细胞信号传导途径，调节轴突生长重要基因的表达。在成年大鼠中，肌苷刺激主要皮质通路的重组后，横断特定的纤维束或单侧中风后。这种重组允许来自完整半球的投射部分地重新神经支配失去正常输入的脑干和脊髓区域，并导致改善的行为结果。目的1将研究是否有助于克服轴突生长抑制影响的药物可以增强肌苷对神经重组和行为结果的影响。目的2将研究单侧脑损伤后的强化训练本身是否促进轴突重组，以及这种训练是否会增强肌苷治疗的效果。最后，脑损伤后有一个有限的时间窗，在此时间窗内必须开始肌苷治疗以获得持久的益处。目标3将试图确定基因的表达，使神经元响应肌苷在这一“机会之窗”，以及基因表达的结果，肌苷治疗在这一时期。这将使用激光捕获显微切割来分离皮质锥体细胞和微阵列来鉴定其表达被选择性改变的基因。目标3的第二部分将使用基因治疗方法来研究改变皮质锥体细胞中与轴突生长相关的基因表达的影响。这些研究将增加我们对成熟大脑可塑性的理解，并可能使我们能够改善损伤后的功能结果。

DESCRIPTION (provided by applicant): Recovery from stroke or traumatic brain injury is limited in part by the inability of mature neurons to reorganize their connections significantly. Such reorganization may require both positive stimuli to activate neurons' intrinsic growth state and methods to overcome inhibitory signals that normally suppress growth. Inosine, a purine nucleoside, activates a cellular signaling pathway that regulates the expression of genes important for axon outgrowth. In mature rats, inosine stimulates the reorganization of major cortical pathways after transecting a specific fiber tract or after a unilateral stroke. This reorganization allows projections from the intact hemisphere to partially reinnervate brainstem and spinal cord areas that have lost their normal inputs, and results in improved behavioral outcome. Aim 1 will investigate whether agents that help overcome inhibitory influences on axon growth can enhance the effects of inosine on neural reorganization and behavioral outcome. Aim 2 will investigate whether intensive training after unilateral brain damage itself promotes axonal reorganization, and whether such training will augment the effects of inosine treatment. Finally, there is a limited time window after brain injury in which inosine treatment must begin in order to achieve long-lasting benefits. Aim 3 will attempt to identify genes whose expression enables neurons to respond to inosine during this "window of opportunity", as well as genes that are expressed as a result of inosine treatment during this period. This will be done using laser-capture microdissection to isolate cortical pyramidal cells and microarrays to identify genes whose expression is selectively altered. The second part of Aim 3 will use a gene therapy approach to investigate the effects of altering the expression of genes related to axon growth in cortical pyramidal cells. These studies will increase our understanding of plasticity in the mature brain and potentially enable us to improve functional outcome after injury.