CATECHOLAMINERGIC NEURON PLASTICITY IN AGED BRAIN

形态和功能可塑性的能力， 将使用以下方法评价老年大鼠脑中的儿茶酚胺能（CA）神经元： 作为一个模型系统，一个胺能束接触和调节目标 视上核（SON）的分泌神经元投射到 神经垂体分泌加压素（VP）。 这些传入 含有去甲肾上腺素（NE）的轴突将被神经外科切断， 或者靠近它们在SON处的终止点，或者靠近它们的 起源于中脑腹侧。 病变部位和靶点 检查SON核的新纤维生长和CA神经再支配， 将通过显微荧光分光光度法定量 内源性CA组织荧光和SON CA水平的生化测量 通过高效液相色谱法。 定性评估将 包括顺行束追踪。 目标的功能恢复 通过神经垂体素的免疫细胞化学染色评估神经元， VP、血浆VP放射免疫测定和水平衡监测 （饮水、尿量和渗透压）。 的可能贡献 SON血管的外周交感神经支配到神经再支配 将通过结合上级颈神经节切除术和 每一个神经外科病变，并同时评估 脉管系统和末端荧光的可视化，以及 目标中CA的生物化学和显微荧光光谱定量。 初步研究表明，相当大的能力，形态 再生保留在老年人的大脑;拟议的项目将 提供相关的解剖学和功能评估。

The capacity for morphological and functional plasticity of catecholaminergic (CA) neurons in aged rat brain will be evaluated, using as a model system an aminergic tract which contacts and regulates target secretory neurons in the supraoptic nucleus (SON) which project to the neurohypophysis and secrete vasopressin (VP). These afferent norepinephrine (NE) containing axons will be neurosurgically severed, either near their point of termination at the SON, or near their cells of origin in the ventral mesencephalon. The lesion sites and the target nucleus, SON, will be examined for new fiber growth and CA reinnervation, which will be evaluated by microspectrofluorometric quantitation of endogenous CA histofluorescence, and biochemical measure of SON CA levels by high performance liquid chromatography. Qualitative assessment will include anterograde tract tracing. Functional restoration in the target neurons will be assessed by immunocytochemical staining of neurophysin and VP, radioimmunoassay of plasma VP, and monitoring of water balance (drinking, and urine volume and osmolality). The possible contribution of peripheral sympathetic innervation of SON vasculature to the reinnervation pattern will be tested by combining superior cervical ganglionectomy with each of the neurosurgical lesions, and evaluation by simultaneous visualization of vasculature and terminal fluorescence, as well as biochemical and microspectrofluorometric quantitation of CA in the target. Preliminary studies indicate that a considerable capacity for morphological regeneration is retained in the aged brain; the proposed project will provide a correlative anatomical and functional assessment.