Modulating Post-Injury Gliotransmitter Levels Leads to Improved Synaptic Function

描述(申请人提供)：创伤性脑损伤(TBI)导致许多急性病理改变，包括细胞外释放谷氨酸3-5。这种急剧的递质释放被认为在早期神经细胞死亡中起着重要作用，7。虽然进行性突触损伤在功能丧失中也起着重要作用8，但不幸的是，我们对脑损伤后几天和几周内递质调节的了解有限。神经胶质细胞，特别是星形胶质细胞，通过调节突触间隙9-12的递质水平，在维持突触完整性和损伤后的功能方面发挥着重要作用。此外，受体酪氨酸激酶家族，EPH受体，及其同源配体，肾上腺素，调节突触功能和形成，以及从星形胶质细胞合成和释放递质13-17。我们推测，神经元与星形胶质细胞之间的联系是通过EphB3-EphB3信号来调节突触中的神经胶质递质水平，通过增强EphB3信号，我们可以改善脑损伤后突触的稳定性和功能。在这项研究中，我们将研究通过遗传操作星形胶质细胞和/或神经元中的递质酶(即丝氨酸外消旋酶)和ewitinB3-EphB3信号来改变递质水平如何影响脑损伤后突触的稳定性和功能。我们将采取全面的方法和利用尖端技术来测量突触传递、递质释放、蛋白质表达的生化变化，以及使用功能获得和功能丧失的小鼠模型的学习和记忆行为。

DESCRIPTION (provided by applicant): Traumatic brain injury (TBI) results in a number of acute pathological alterations including the extracellular release of glutamate3-5. This acute transmitter release is thought to play a significant role in early neuronal cell death6,7. Although progressive synaptic damage also plays a significant role in functional loss8, and unfortunately our understanding of transmitter regulation in the days and weeks after TBI is limited. Glial cells in particular astrocytes, play an important role in maintaining synaptic integrity and function aftr injury by regulating transmitter levels in the synaptic cleft9-12. In addition, a family of recepto tyrosine kinases, Eph receptors, and their cognate ligands, ephrins, regulates synaptic function and formation as well as transmitter synthesis and release from astrocytes13-17. We hypothesize that neurons communicate with astrocytes through ephrinB3-EphB3 signaling to regulate glial transmitter levels in the synapse, and through enhancement of EphB3 signaling we can improve synaptic stability and function after TBI. In this study, we will examine how varying transmitter levels through genetic manipulation of transmitter enzymes (i.e. serine racemase) and ephrinB3-EphB3 signaling in astrocytes and/or neurons affects synaptic stability and function after TBI. We will take a comprehensive approach and make use of cutting-edge techniques to measure synaptic transmission, transmitter release, biochemical alterations in protein expression, and learning and memory behavior using gain-of-function and loss-of-function mouse models.