STEROIDS AS TROPHIC FACTORS--AGING NEUROMUSCULAR SYSTEM

使用一个简单的神经肌肉系统，这个建议的重点是 雄激素对维持运动神经元数量的影响， 形态学和衰老中的功能。 该系统由两个性别组成 在大鼠脊髓的二形核，脊髓的脊核， 球海绵体肌（SNB）和背外侧核（DLN）和肌肉 它们所支配的会阴。 虽然存在于男性这些核和 女性的目标肌肉减少或缺失。 雄激素是一种 营养功能的发展和成人维持这一系统， 例如调节神经元数量和树突生长， 发育，维持运动神经元形态， 成年期的突触学 提出的实验检查的影响， 随着年龄的增长，雄激素水平下降， 类固醇敏感的运动神经元 这三个不同的特征 将检查运动神经元群体：运动神经元数量，形态， 和功能 运动神经元数量将在一系列时间进行评估 对应循环雄激素自然变化的点， 性二态和非二态类固醇敏感人群， 确定雄激素的下降是否反映在 运动神经元 通过维持雄激素水平或加速他们的 下降时，雄激素对运动神经元存活的影响将是 直接评估。 回归变化的正常时间过程和 将检验与年龄相关的雄激素下降的因果关系。 运动神经元形态结构可塑性的保持也将 被确定。 最后，功能方面的类固醇积累和 兴奋性将根据年龄和激素的变化进行评估 条件 因为在成熟的哺乳动物中神经元是不可替代的 神经系统，了解控制死亡的因素 衰老过程中的神经元对于我们理解衰老过程至关重要 以及与年龄相关的神经行为功能下降。

Using a simple neuromuscular system, this proposal focuses on the influence of androgens in the maintenance of motoneuron number, morphology, and function in aging. This system consists of two sexually dimorphic nuclei in the rat spinal cord, the spinal nucleus of the bulbocavernosus (SNB) and the dorsolateral nucleus (DLN) and the muscles of the perineum they innervate. While present in males these nuclei and their target muscles are reduced or absent in females. Androgens serve a trophic function in the development and adult maintenance of this system, for example regulating neuron number and dendritic growth during development, and maintaining motoneuron morphology and synaptology in adulthood. The experiments proposed examine the effect of the declines in androgen levels that occur with advancing age on these steroid-sensitive motoneurons. Three different features of these motoneuron populations will be examined: motoneuron number, morphology, and function. Motoneuron number will be assessed at a series of time points corresponding to the natural changes in circulating androgen in both sexually dimorphic and nondimorphic steroid-sensitive populations, to determine whether declines in androgen are reflected in the loss of motoneurons. By maintaining androgen levels or accelerating their decline, the influence of androgens on motoneuron survival will be directly assessed. The normal time course of regressive changes and the causal relation with age-related declines in androgens will be tested. The retention of structural plasticity in motoneuron morphology will also be determined. Finally, functional aspects of steroid accumulation and excitability will be assessed with regard to changes with age and hormonal condition. Because neurons can not be replaced in mature mammalian nervous systems, understanding the factors which control the death of neurons in aging is critical for our understanding of the aging process and age-related declines in neurobehavioral function.