SYNAPTIC REMODELING OF THE STRIATUM AFTER DEAFFERENTATION

这个项目试图确定调节细胞的细胞机制 大鼠纹状体(ST)突起生长与突触替代 对损伤的反应以及老化对这些过程的影响。研究 在上一个供资期间进行的调查支持这样一种信念，即 反应性突触发生的细胞基础涉及激活 部分重叠的发育信号的特定集合 细胞类型、脑区域和病变特异性，这些反应可能 因年龄而受到不同程度的影响。然而，尽管之前的解剖学 研究已经很容易地证明了神经元形成新的 突触回路对脑损伤反应的细胞机制 调节反应性突触发生的机制尚不清楚。 拟议的研究是已完成工作的直接延伸 之前并将检验四个一般假设：1)不同的集合 生长相关蛋白调控神经突起的生长 皮质纹状体神经元对不同去传入损伤的反应： 2)碎片清除、终端扩散和 损伤后ST段的突触替换受年龄和年龄的影响 病变类型；3)突触神经支配的新模式 在ST形成的皮质损伤后是不同的， 黑质或两者兼而有之，并反映在药理学上 纹状体神经元上突触输入的特性；以及4) 慢性饮食限制或使用多巴胺激动剂治疗 培高利特控制ST段老化的影响(即反应性 星形胶质细胞增多症，D2受体缺失)将逆转衰老对 皮质损伤后可见树突重塑和突起生长。 我们将在年轻人(4个月)和老年人中使用实验性的去传入损伤。 (24个月)大鼠建立不同神经递质组合模型 可能影响神经突起生长和突触替代的缺陷 脑损伤后的ST。此外，我们将对老化的大鼠进行预先筛查 到外科手术，使用平衡木测试，以确定老年大鼠的亚群 黑质纹状体缺陷可能会改变他们的反应能力 损伤。我们还将评估功能恢复率以 与我们的形态和分子数据相关联。形态 ST传入输入的重建将使用以下方法进行评估 超微结构方法；而突触生理学的解剖学 重组ST段将通过电生理分析进行检测。在……里面 此外，我们还将采用原位杂交和蛋白质印迹等方法 确定mRNAs和蛋白质水平变化的时间进程 我们的假设与轴突的促进有关 ST段的突起和突触替换(即SCG-10，GAP-43，BDNF， GDNF等)。

This project seeks to identify the cellular mechanisms that regulate neurite outgrowth and synapse replacement in the striatum (ST) in response to injury and the effect of aging on these processes. Studies conducted during the previous funding period support the belief that the cellular basis of reactive synaptogenesis involves the activation of specific sets of partially overlapping developmental signals that are cell type, brain region and lesion specific, and that these responses may be differentially affected by age. However, while previous anatomical studies have readily demonstrated the ability of neurons to form new synaptic circuits in response to brain injury the cellular mechanisms that regulate reactive synaptogenesis remain unclear. The studies proposed are a direct extension of the work completed previously and will test four general hypotheses: 1) that different sets of growth associated proteins regulate neurite outgrowth in corticostriatal neurons in response to different deafferentation lesions: 2) that the time course for debris removal, terminal proliferation and synapse replacement in the ST after injury is influenced by age and the type of lesion involved; 3) that the new pattern of synaptic innervation that is formed in the ST is different after lesions of the cortex, substantia nigra or both, and are reflected in the pharmacological properties of the synaptic input on striatal neurons; and 4) that chronic dietary restriction or treatment with the dopamine agonist pergolide to manipulate the effects of aging in the ST (i.e., reactive astrocytosis, loss of D2 receptors) will reverse the effects of aging on dendrite remodeling and neurite outgrowth found after the cortex lesion. We will use experimental deafferentation lesions in young (4 mos) and old (24 mos) rats to model different combinations of neurotransmitter deficits that may effect neurite outgrowth and synapse replacement in the ST following brain injury. In addition, we will screen aged rats prior to surgery, using the balance beam test, to identify subsets of old rats with nigrostriatal deficits that may alter their ability to respond to the lesion. We will also assess the rate of functional recovery to correlate with our morphological and molecular data. Morphological remodeling of afferent input to the ST will be evaluated using ultrastructural methods; while synaptic physiology of the anatomically reorganized ST will be examined by electrophysiological analysis. In addition, we will use in in situ hybridization and western blot methods to define the time course of changes in the levels of mRNAs and proteins that we hypothesize are associated with the promotion of neurite outgrowth and synapse replacement in the ST (i.e., SCG-10, GAP-43, BDNF, GDNF, etc.).