ALTERED EXCITATORY NEUROTRANSMISSION AFTER BRAIN TRAUMA

描述(申请人提供)：创伤性脑损伤(TBI)导致认知和运动障碍，涉及兴奋性神经传递和可塑性改变，包括长时程增强(LTP)丧失。兴奋性突触功能异常可由网络回路、突触数目或形态、和/或突触前或突触后神经元功能改变引起。本研究的总体目标是从电生理、生化和分子水平上了解脑损伤引起兴奋性传递改变的机制。我们的假设是，脑损伤后突触后谷氨酸受体的性质和/或调节的改变导致了脑损伤后存活神经元的突触功能和信息处理的改变。在体外，创伤导致神经元谷氨酸受体产生高度新颖的变化，谷氨酸受体介导兴奋性突触传递和可塑性。膜片钳电生理、共聚焦显微镜、免疫细胞化学和Western印迹分析将用于研究体外拉伸模型下亚致死性损伤的大脑皮层和海马锥体神经元。我们将确定损伤引起的兴奋性突触后电流的变化是否是由于突触后AMPA和NMDA受体的直接变化，并确定涉及的特定细胞内信号系统，我们推测可能包括钙/钙调蛋白激酶II和PKC。此外，我们将确定在基础突触传递过程中以及在正常诱导突触可塑性的条件下，损伤后这些细胞内通路的激活是否会导致谷氨酸受体异常磷酸化。实现这些特定的目标将阐明机械损伤如何改变皮层和海马区的兴奋性突触传递和突触调节，并确定这些变化是否由突触后谷氨酸受体的变化所介导，包括受体异常磷酸化。了解脑损伤后特定脑区突触传递异常的分子机制可能有助于脑损伤新疗法的开发，并有助于指导体内脑损伤后认知和运动障碍的未来研究。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) results in cognitive and motor deficits involving altered excitatory neurotransmission and plasticity, including a loss of long term potentiation (LTP). Abnormal excitatory synaptic function could result from changes in network circuitry, synapse number or morphology, and/or presynaptic or postsynaptic neuronal function. The overall objective of our research is to understand the mechanisms involved in TBI-induced alterations of excitatory transmission at the electrophysiological, biochemical and molecular level. Our hypothesis is that TBI-induced changes in the properties and/or regulation of postsynaptic glutamate receptors contribute to the alterations in synaptic function and information processing observed in surviving neurons after TBI. In vitro traumatic injury produces highly novel changes in neuronal glutamate receptors, which mediate excitatory synaptic transmission and plasticity. Patch clamp electrophysiology, confocal microscopy, immunocytochemistry, and Western blot analysis will be used to study cultured cortical and hippocampal pyramidal neurons sub lethally injured using the in vitro stretch model. We will determine whether injury-induced changes in excitatory postsynaptic currents are due to direct alterations in postsynaptic AMPA and NMDA receptors and identify the specific intracellular signaling systems involved, which we hypothesize may include calcium/calmodulin kinase II, and PKC. Furthermore, we will determine whether activation of these intracellular pathways following injury leads to abnormal glutamate receptor phosphorylation during basal synaptic transmission and under conditions that normally induce synaptic plasticity. Carrying out these Specific Aims will elucidate how mechanical injury alters excitatory synaptic transmission and synaptic regulation in both the cortex and hippocampus and determine if these alterations are mediated by changes in postsynaptic glutamate receptors, including abnormal receptor phosphorylation. An understanding of the molecular mechanisms responsible for abnormal synaptic transmission in specific brain regions following TBI may assist in the development of new TBI treatments and will help direct future research of cognitive and motor deficits following in vivo TBI.