Developmental Regulation of Motor Neuron Dendrite Plasticity by Glutamate Receptors

神经细胞或神经元主要在其树突内接受来自其他神经元的输入，树突是源自细胞体的高度分支结构。在许多神经元中，树突的模式在发育过程中通过一个依赖于输入神经元活动的过程被完善。这个过程被假设为消除部分接受错误输入的树突，从而“硬连接”神经元以获得最大的效率。该项目采用含有脊髓运动神经元的培养物来研究这些神经元如何利用电活动来完成树突的细化。将进行实时成像，以检查树突片段的生长，伸长和消除的速度如何受到神经递质谷氨酸结合到细胞表面特定谷氨酸受体的影响。荧光标记的谷氨酸受体将被引入神经元，以确定它们是否在动态生长或树突收缩区域共定位。此外，将使用定量PCR方法测量每种受体的基因表达水平，以确定在运动神经元发育过程中如何控制每种受体的可用性。最后，将通过实验降低谷氨酸受体的表达水平，以研究树突生长是否受到损害。这些研究很重要，因为它们将提供关于发育中的神经元如何通过改变它们对神经递质的反应能力来获得连接模式的信息。该提案的广泛影响包括显著提高杜兰大学的研究生和本科生奖学金和研究。将当前的研究策略整合到研究生和本科生的培训和课堂讨论中，将促进神经科学成为整个高等教育系统的研究主题。

Nerve cells, or neurons, receive inputs from other neurons predominantly within their dendrites, highly branched structures emanating from the cell body. In many neurons, the patterns of dendrites are refined during development, through a process that is dependent on the activity of the input neurons. This process has been hypothesized to eliminate parts of the dendrites that receive erroneous inputs, thus "hardwiring" the neurons for maximal efficiency. This project employs cultures containing spinal cord motor neurons to investigate how these neurons use electrical activity to accomplish refinement of their dendrites. Real-time imaging will be performed to examine how rates of growth, elongation and elimination of dendritic segments are affected by the neurotransmitter glutamate binding to specific glutamate receptors on the cell surface. Fluorescent-tagged glutamate receptors will be introduced into neurons, to determine whether these are co-localized at areas of dynamic growth or retraction of dendrites. In addition, level of gene expression for each receptor will be measured using a quantitative PCR method, to determine how the availability of each receptor is controlled during the development of motor neurons. Finally, levels of glutamate receptor expression will be experimentally reduced, to investigate whether dendrite growth is compromised. These studies are important because they will provide information regarding how developing neurons attain patterns of connectivity by altering their ability to respond to neurotransmitters.The broader impact of this proposal includes significant enhancement of graduate and undergraduate scholarship and research at Tulane University. The integration of current research strategies into graduate and undergraduate training and classroom discussions will promote neuroscience as a subject for study throughout the higher education system.