NEURONAL PLASTICITY AND THYROID HORMONE

拟议的研究将确定甲状腺激素在 轴突的萌发和其他神经回路的变化 可可三文鱼中的熏香。这项提议是由以下因素推动的 初步实验表明，熏蒸是 与视觉和嗅觉的剧烈变化有关 途径，2)脑内5-羟色胺含量增加，3)增加 在大脑中结合甲状腺激素的能力。 嗅化是甲状腺激素发挥作用的一种变态。 一个重要的角色。它的特点是1)行为的变化， 2)出生流上的嗅觉印记，3)大体变化 外观和4)渗透调节能力的变化。 嗅觉是特别有趣的，因为它似乎是 可逆的。 这项拟议的研究是一项长期计划的一部分 将鲑鱼作为研究可塑性的模型， 大脑的再生和老化将包括表征 黄曲霉的光镜、超微结构和化学变化 在熏蒸过程中的大脑。这项研究有直接的影响 以了解人脑回路的变化，因为 这些数据将提供有关甲状腺作用的信息 神经可塑性中的激素。研究结果将进一步阐明 在神经可塑性中什么是普遍的，什么是独特的。变化 在三文鱼中更容易被检测到 哺乳动物的大脑，使三文鱼成为 对发芽的操纵。 拟议的实验将包括三个比较 鲑鱼种群。甲状腺抑制，甲状腺激素治疗，以及 正常的鱼将在之前、期间和之后进行频繁采样 蜕变。1)嗅觉和视网膜投射的变化 将用HRP、赖氨酸钴和电子进行测定 显微技术。2)超微结构定量研究 视顶盖将定义突触密度的变化和 突触类型。3)脑内儿茶酚胺和 氨基酸类神经递质将用高效液相色谱法测定 技巧。4)5-羟色胺能和毒碱能胆碱能神经元 将以免疫组织化学和 放射自显影方法。5)高尔基研究将在#年进行 对神经元形态变化的研究。6)受体结合 三碘甲腺原氨酸的动力学将在分离的细胞上测定 核和定量放射自显影方法将用于 测量甲状腺激素受体结合量的变化 组织切片。

The proposed studies will define the role of thyroid hormone in the sprouting of axons and other circuitry changes during smoltification in coho salmon. The proposal is prompted by preliminary experiments which show that smoltification is associated with 1) dramatic changes in visual and olfactory pathways, 2) increases in brain serotonin content and 3) increases in brain thyroid hormone binding capacity. Smoltification is a metamorphosis in which thyroid hormone plays an important role. It is characterized by 1) changes in behavior, 2) olfactory imprinting on the natal stream, 3) changes in general appearance and 4) changes in osmoregulatory capacity. Smoltification is of particular interest because it appears to be reversible. The proposed research, which is part of a long range plan to develop salmon as a model for research on plasticity, regeneration, and aging of the brain, will include characterizing light microscopic, ultrastructural and chemical changes of the brain during smoltification. The research has direct implications for understanding changes in circuitry in the human brain because the data will provide information about the role of thyroid hormone in neural plasticity. The results will further elucidate what is universal in neural plasticity and what is unique. Changes in circuits are much easier to detect in salmon than any mammalian brain, making the salmon a ideal model for manipulation of sprouting. The proposed experiments will involve a comparison of three populations of salmon. Thyroid inhibited, thyroxine treated, and normal fish will be sampled frequently before, during and after metamorphosis. 1) Changes in olfactory and retinal projections will be determined with HRP, cobalt lysine and electron microscopic techniques. 2) Quantitative ultrastructural studies of the optic tectum will define changes in the synaptic densities and synaptic types. 3) Changes in brain content of catecholamine and amino acid neurotransmitters will be determined with HPLC techniques. 4) Serotonergic and muscarinic cholinergic neurons will be characterized with immunohistochemical and autoradiographic methods. 5) Golgi studies will be carried out in a search for changes in neuronal morphology. 6) Receptor binding kinetics of triiodothyronine will be determined on isolated cell nuclei and quantitative autoradiographic methods will be used to measure changes in thyroid hormone receptor binding capacity on histological sections.