TROPHIC FACTOR-INDUCED SYNAPTIC REGROWTH IN THE CNS

本提案的长期目标是确定 营养因子诱导的大脑突触重塑的局限性 病变动物的皮质。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以及 (2)神经营养因子可能的治疗用途。这项研究 小组证明，改变皮质梗塞，给予 神经生长因子导致萎缩的胆碱能输入再生 皮层数量的增加表现为 胆碱能静脉曲张，突触前元件的大小和 突触接触的数量。在拟议的研究中，我们将 解决以下问题：这些变化的范围有多大 皮质套；它们是针对胆碱能系统的吗？确实 突触重塑在治疗结束时持续存在；这些事件可以 也可在老年动物受损的中枢神经系统中诱导。这些研究将 在年轻成年和老年 Fischer 344 大鼠中进行。皮质 将在麻醉动物上进行断血管损伤。安 Alzet 微型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 置于对侧侧脑室。经过一星期的治疗后 （对于老年动物则需要更长的时间）微型泵将被移除并且 动物可以存活不同的时间。皮质胆碱能 将通过光学和电子显微镜研究光纤网络 借助图像分析进行定量免疫细胞化学。 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 病变边缘。此外，去甲肾上腺素能和 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 关于皮质突触回路。突触后胆碱能的研究 剩余皮质中的目标将使用双标记进行 光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与 谷氨酸、GABA、生长抑素和 VIP 的免疫细胞化学检测 每个递质上胆碱能突触的相对百分比 特定的突触后目标将通过定量电子进行评估 显微镜。这些研究应该提供相关的重要信息 潜在使用神经营养剂来治疗的问题 长期的神经退行性疾病，假设 除了受损的核周体的恢复外，刺激和 维护新形成的突触，作为丢失电路的替代品， 是一个理想的效果。

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.