Homeostatic Regulation of Supraoptic Neurons: Role of BDNF

描述（由申请人提供）：这些研究的目的是确定脑源性神经营养因子（BDNF）及其受体TrkB如何影响加压素释放，以进行性生理挑战，缺水。我们的数据表明，脑源性神经营养因子可以促进谷氨酸和GABA信号在水剥夺引起磷酸化NR 2B和增加氯转运蛋白KCC 2的表达。增加NR 2B磷酸化将增加NMDA受体活化，从而增强加压素释放，而增加KCC 2活性可增加GABA的抑制作用，这代表了在缺水期间对增加的兴奋的稳态突触补偿。具体目标1：以确定神经垂体BDNF-TrkB信号传导的作用和通过NR 2B磷酸化增强的谷氨酸作用在由水剥夺诱导的持续加压素释放期间。假设：由于NR 2B NMDA受体亚单位通过Fyn激酶磷酸化，与缺水相关的TrkB磷酸化导致谷氨酸活性增强，Fyn激酶是Src激酶家族的一员，有助于NMDA介导的MNCs可塑性具体目标2：检验神经垂体BDNF-TrkB信号传导增强GABA在缺水期间的抑制作用的假设。假设：在水剥夺期间BDNF-TrkB信号传导增加KCC 2表达，增强GABA在MNCs中通过Src激酶的抑制作用，而不激活磷脂酶C γ。方法：这些实验将首次确定BDNF-TrkB信号在持续AVP释放的稳态调节中的作用。将采用综合方法，包括在体外和体内电生理实验，整体动物实验中，TrkB和Src激酶拮抗剂将局部应用于SON，和水平衡和AVP释放在大鼠的功能研究。受益：这些实验将解决我们对神经垂体功能生理调节的理解中存在的差距。这些实验的发现可能会改变加压素释放不当的临床研究和概念化的方式。

DESCRIPTION (provided by applicant): The goal of these studies is to determine how Brain derived neurotrophic factor (BDNF) and its receptor TrkB influence vasopressin release to a progressive physiological challenge, water deprivation. Our data suggest that BDNF may facilitate both glutamate and GABA signaling during water deprivation by causing phosphorylation NR2B and increasing the expression of the chloride transporter KCC2. Increased NR2B phosphorylation would increase NMDA receptor activation enhancing vasopressin release while increased KCC2 activity could increase the inhibitory effects of GABA representing a homeostatic synaptic compensation to increased excitation during water deprivation. Specific Aim 1: to determine the role of neurohypophysial BDNF-TrkB signaling and enhanced glutamate action through NR2B phosphorylation during sustained vasopressin release induced by water deprivation. Hypothesis: Phosphorylation of TrkB associated with water deprivation leads to enhanced glutamate activity due to phosphorylation of NR2B NMDA receptor subunits through Fyn kinase, a member of the Src kinase family contributing to NMDA mediated plasticity in MNCs Specific Aim 2: to test the hypothesis that neurohypophysial BDNF-TrkB signaling enhances the inhibitory effects of GABA during water deprivation. Hypothesis: BDNF-TrkB signaling during water deprivation increases KCC2 expression enhancing the inhibitory effects of GABA in MNCs via Src kinase and without the activation of Phospholipase C gamma. Methods: These experiments will for the first time define the roles of BDNF-TrkB signaling in the homeostatic regulation of sustained AVP release. An integrative approach will be employed that includes in vitro and in vivo electrophysiological experiments, whole animal experiments in which TrkB and Src kinase antagonists will be locally applied to the SON, and functional studies of water balance and AVP release in the rat. Benefit: These experiments will address an existing gap in our understanding of the physiological regulation of neurohypophyseal function. The findings of these experiments could potentially alter the way that inappropriate vasopressin release is studied and conceptualized clinically.