TROPHIC FACTOR-INDUCED SYNAPTIC REGROWTH IN THE CNS

本提案的长期目标是确定 营养因子诱导的脑内突触重构的局限性 受损动物的大脑皮质。拟议的研究解决了两个关键问题 问题：(L)受损中枢神经系统功能恢复的程度和 (2)神经营养因子的可能治疗应用。这项研究 小组证明，在皮质梗塞后，给药 神经生长因子导致萎缩的胆碱能输入的再生 到皮质，表现为皮质细胞数量的增加 胆碱能静脉曲张，突触前成分的大小和 突触接触的数量。在拟议的研究中，我们将 回答以下问题：这些变化在多大程度上 皮质外套膜；它们是胆碱能系统所特有的吗； 突触重构在治疗结束后持续存在；这些事件 在老年动物损伤的中枢神经系统也有诱导作用。这些研究将 在青年大鼠和老年Fischer 344大鼠身上进行。大脑皮层 切断血管损伤将在麻醉动物身上进行。一个 阿尔茨海默病微泵，含有载体或推定的神经营养剂 (神经生长因子和/或GM1)将连接到永久插管 放置在对侧侧脑室。经过一周的治疗 (对于年老的动物，则为更长时间)小型泵将被移除，而 动物被允许存活不同的时间。皮质胆碱能 将用光学和电子显微镜研究纤维网络。 定量免疫细胞化学，结合图像分析。 要评估的参数是光纤网络的密度、 静脉曲张的数量和大小以及突触的数量。这些研究 将在剩余的皮质中进行，距离 病变的边缘。此外，去甲肾上腺素和 将研究生长抑素免疫反应网络以评估 神经营养因子诱导效应的神经化学特异性 在大脑皮层突触回路上。突触后胆碱能的研究 剩余皮质中的靶点将使用双重标记进行 光镜和电子显微镜免疫细胞化学。为此， 胆碱乙酰转移酶免疫细胞化学将结合 谷氨酸、GABA、生长抑素和血管活性肠肽的免疫细胞化学检测 各递质上胆碱能突触的相对百分比 具体的突触后靶点将通过定量电子来评估 显微镜。这些研究应提供有关的重要信息 关于可能使用神经营养剂治疗的问题 长期的神经退行性疾病，假设 除了修复受损的骨膜外，刺激和 维持新形成的突触，作为丢失回路的替代品， 是一种理想的效果。

The long term objectives of the present proposal are to determine the limits of trophic factor-induced synaptic remodelling in the cerebral cortex of lesioned animals. The proposed research addresses two key issues: (l) the extent of functional restoration in the damaged CNS and (2) the possible therapeutic use of neurotrophic factors. This research group demonstrated that, alter cortical infarct, the administration of nerve growth factor causes a regrowth of the atrophied cholinergic input to the cortex as manifested by an increase in the number of cortical cholinergic varicosities, in the size of the presynaptic elements and in the number of synaptic contacts. In the proposed research, we will address the following questions: how widespread are these changes in the cortical mantle; are they specific for the cholinergic system; does synaptic remodelling persist alter the end of therapy; can these events also be induced in the injured CNS of aged animals. These studies will be carried out in young adult and aged Fischer 344 rats. Cortical devascularizing lesions will be performed on anesthetized animals. An Alzet minipump containing either vehicle or putative neurotrophic agents (nerve growth factor and/or GM1) will be connected to a permanent cannula placed in the contralateral lateral ventricle. After one week of therapy (or longer for aged animals) the minipumps will be removed and the animals allowed to survive for various times. The cortical cholinergic fiber network will be studied by means of light and electron microscopy quantitative immunocytochemistry, with the help of image analysis. Parameters to be assessed are the density of the fiber network, the number and size of varicosities and number of synapses. These studies will be carried out in the remaining cortex, at several distances from the edge of the lesion. Furthermore, the noradrenergic and the somatostatin-immunoreactive networks will be studied in order to assess the neurochemical specificity of the neurotrophic factor induced effects on cortical synaptic circuits. Studies of the postsynaptic cholinergic targets in the remaining cortex will be carried out using double-labeling light and electron microscopic immunocytochemistry. For this purpose, choline acetyltransferase immunocytochemistry will be combined to the immunocytochemical detection of glutamate, GABA, somatostatin and VIP and the relative percentage of cholinergic synapses on each transmitter specific postsynaptic target will be assessed by quantitative electron microscopy. These studies should provide important information relevant to the issue of the potential use of neurotrophic agents to treat neurodegenerative diseases on a long term basis, on the assumption that besides the recovery of damaged perikarya, the stimulation and maintenance of neoformed synapses, as a replacement for lost circuits, is a desirable effect.