VGLUT2 Transmission in Prefrontal Cortex and Working Memory

抽象的。精神分裂症是一种发育障碍，假设包括 谷氨酸能功能、N-甲基-D-天冬氨酸受体(NMDAR)信号异常及其改变 内侧前额叶皮质的兴奋性/抑制性(E/I)平衡。取得进展的关键障碍 改善治疗和预防精神分裂症的策略是对以下方面的作用缺乏了解 皮质内源性囊泡谷氨酸向GABA能中间神经元释放突触前谷氨酸 转运蛋白2(VGLUT2)突触在调节E/I平衡中的作用及其对PV成熟的影响 含有中间神经元的。我们的目标是通过以下方式改进精神分裂症的治疗和预防策略 发展和理解VGLUT2介导的谷氨酸释放的作用和影响 关于光伏抑制系统的功能障碍。我们的中心假设是VGLUT2提供谷氨酸 对mPFC内的新皮质PV+抑制中间神经元的影响，这对MPFC的成熟起重要作用 兴奋/抑制(E/I)平衡和工作记忆。我们的目标是(1)建立 VGLUT2突触在体内和体外靶向mPFC中的PV+神经元间系统，(2)证明 VGLUT2突触的丢失减少了E-I突触的谷氨酸释放并抑制了抑制性 (3)表明条件性VGLUT2基因敲除(KO)小鼠在工作记忆中表现出缺陷。 我们的预期结果将是(1)理解固有的皮质VGLUT2突触与 E/I平衡，因为它们以经常性的抑制性反馈神经元为靶点，并表现出活性依赖的释放 谷氨酸，(2)条件性VGLUT2 KO小鼠内源性皮质VGLUT2表达缺失的知识 导致PV+中间神经元GAD67的减少，并抑制突触传递 锥体神经元，以及(3)确认VGLUT2编码在皮质边缘回路的传递对 工作记忆。这些结果对我们的精神分裂症的治疗和预防策略的影响 结果将提供是对相关认知障碍的治疗洞察的重要一步 以及VGLUT2介导的释放在精神分裂症中的作用和影响的理解 PV-神经元间系统的成熟和E/I平衡。目标1将检验这样一种假设，即固有的皮质 VGLUT2突触与E/I平衡有关，因为a)它们以PV+GABA能中间神经元为靶标，b)它们 表现出活性依赖的谷氨酸释放，以及c)它们的丢失抑制了突触传递 MPFC。我们将利用GAD67gfp+转基因小鼠在PV+中间神经元中选择性表达EGFP 免疫荧光和电生理学研究。目标2将检验VGLUT2编码的假设 在发育过程中，皮质边缘回路中的兴奋性传递对成年人的工作记忆至关重要，通过 在T迷宫中使用连续延迟交替任务评估工作记忆功能 VGLUT2失活发生在发育早期的小鼠和青春期小鼠。

Abstract. Schizophrenia is a developmental disorder that is hypothesized to include alterations in glutamatergic function, aberrant N-methyl-D-aspartic acid receptor (NMDAR) signaling and altered excitatory/inhibitory (E/I) balance in the medial prefrontal cortex (mPFC). A critical barrier to progress in improving strategies for the treatment and prevention of schizophrenia is a lack of understanding of the role of presynaptic glutamate release onto GABAergic interneurons by intrinsic cortical vesicular glutamate transporter-2 (VGLUT2) synapses in regulating E/I balance and how this may impact the maturation of PV- containing interneurons. Our goal is to improve strategies for the treatment and prevention of schizophrenia by developing and providing an understanding of the role and influence of VGLUT2-mediated glutamate release on the dysfunction of the PV-inhibitory system. Our central hypothesis is that VGLUT2 provides glutamate to neocortical PV+ inhibitory interneurons in the mPFC that is important for the maturation of excitatory/inhibitory (E/I) balance and to working memory. Our objectives are to (1) establish that functional VGLUT2 synapses target the PV+ interneuronal system in mPFC in vivo and in vitro, (2) demonstrate that the loss of VGLUT2 synapses decreases glutamate release at E-I synapses and suppresses inhibitory transmission, and (3) show that conditional VGLUT2 knockout (KO) mice display deficits in working memory. Our expected outcomes will be (1) an understanding that intrinsic cortical VGLUT2 synapses are relevant to E/I balance because they target recurrent inhibitory feedback neurons and exhibit activity-dependent release of glutamate, (2) the knowledge that loss of intrinsic cortical VGLUT2 expression in conditional VGLUT2 KO mice leads to a reduction in GAD67 in PV+ interneurons and suppresses inhibitory synaptic transmission onto pyramidal neurons, and (3) to affirm that VGLUT2-encoded transmission in corticolimbic circuits is critical to working memory. The impact of these results on strategies for treating and preventing schizophrenia that our outcomes will provide is an important step towards therapeutic insight into the cognitive impairment associated with schizophrenia and an understanding of the role and influence of VGLUT2-mediated release on the maturation of the PV-interneuronal system and E/I balance. Aim 1 will test the hypothesis that intrinsic cortical VGLUT2 synapses are relevant to E/I balance because a) they target PV+ GABAergic interneurons, b) they exhibit activity-dependent release of glutamate, and c) their loss suppresses inhibitory synaptic transmission in the mPFC. We will utilize GAD67gfp+ transgenic mice that selectively express EGFP in PV+ interneurons for immunofluorescence and electrophysiologic studies. Aim 2 will test the hypothesis that VGLUT2-encoded excitatory transmission in corticolimbic circuits during development is critical to working memory in adults, by assessing working memory function using the continuous delayed alternation task in a T-maze in two lines of mice where VGLUT2 inactivation occurs early in development and in adolescent mice.