Neuronal regulation of glutamate homeostasis

谷氨酸稳态的神经调节

• 批准号: 8893512
• 负责人: PAUL ALLEN ROSENBERG
• 金额: $ 27.9万
• 依托单位: BOSTON CHILDREN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 2015
• 资助国家: 美国
• 起止时间: 2015-04-17 至 2017-02-28
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/8893512
• 关键词: Acute; Affect; Amphetamines; Animals; Anxiety; Astrocytes; Behavior; Behavioral; Biochemical; Brain; Brain region; Cell physiology; Chronic; Cognitive; Defect; Disease; Dopamine; Dopamine D1 Receptor; Dopamine D2 Receptor; Excitatory Synapse; Exposure to; Functional disorder; Gene Expression; Glutamate Transporter; Glutamates; Hippocampus (Brain); Homeostasis; Immediate-Early Genes; Knock-out; Knockout Mice; Light; Locomotion; Measures; Mediating; Membrane Potentials; Mental disorders; Modeling; Molecular; Mus; N-Methyl-D-Aspartate Receptors; N-Methylaspartate; NMDA receptor antagonist; Neurobehavioral Manifestations; Neurons; Parvalbumins; Pathogenesis; Patients; Performance; Phenotype; Preparation; Presynaptic Terminals; Publishing; Regulation; Rest; Role; Schizophrenia; Short-Term Memory; Signal Transduction; Slice; Subchronic Schizophrenia; Symptoms; Synapsins; Synaptic Transmission; Testing; Thalamic structure; Wolves; Work; dopamine transporter; dopaminergic neuron; drug discovery; extracellular; glutamatergic signaling; improved; mind control; novel; nucleus reticularis; object recognition; promoter; public health relevance; recombinase; relating to nervous system; resilience; response; stem; therapeutic target

 DESCRIPTION (provided by applicant): Schizophrenia is a chronic, devastating, psychiatric disorder characterized attributed to abnormalities in dopamine and glutamate signaling. Excitatory circuits control the activity of dopamine neurons, and it is thought that abnormalities in these circuits produce the positive, negative and cognitive features of schizophrenia. Glutamate homeostasis refers to the control of glutamate levels in and around excitatory synapses, and we now have evidence that glutamate homeostasis might be important in controlling the circuits involved in schizophrenia. Glutamate transporters control brain glutamate homeostasis, and the major glutamate transporter in the brain is GLT-1, primarily expressed in astrocytes. Others and we have found that GLT-1 is also expressed in excitatory presynaptic terminals. To understand the function of GLT-1 expressed in neurons, we generated a conditional GLT-1 knockout mouse in which we have used synapsin-cre to accomplish the selective inactivation of GLT-1 in neurons. We have performed extensive behavioral phenotyping of this mouse, including testing responses to amphetamine, which are highly modulated by excitatory signaling and therefore likely, we thought, to be affected by glutamate dyshomeostasis. Previous work by many groups has demonstrated the phenomenon of sensitization to amphetamine, in which behavioral or neural (i.e. dopamine release) effects increase with repeated administration. Amphetamine sensitization is thought to model the cellular processes that underlie the positive symptoms of schizophrenia. Remarkably, we found that inactivation of GLT-1 in neurons produced significant decrease in the acute and sensitized locomotor responses to amphetamine. In addition, we have found improved performance of the nGLT-1 KO in novel object recognition and light-dark emergence. Defects on NOR and LDE may reflect impaired working memory and increased anxiety, components of the cognitive and negative domain of symptoms of schizophrenia. These observations have led us to hypothesize that the nGLT-1 KO may demonstrate resilience to the biochemical and circuit disturbances associated with schizophrenia. We hypothesize further that the phenotype that we observe in the nGLT-1 KO partially stems from changes in ambient glutamate within regions of the brain dependent upon neuronal GLT-1 for glutamate homeostasis. We propose to characterize these phenotypes further to establish whether GLT-1 may be valid target for therapeutic drug discovery. Toward that end, we will: 1) characterize the behavioral phenotype of the nGLT-1 KO mouse subjected to subchronic PCP administration to model symptom domains observed in schizophrenia; 2) characterize the biochemical phenotype of nGLT-1 KO mice; 3) determine the effect of neuronal knockout of GLT-1 on glutamate homeostasis in the nucleus reticularis slice preparation.

 描述（由适用提供）：精神分裂症是一种慢性，毁灭性，精神病，其特征是多巴胺和谷氨酸信号传导异常的特征。兴奋性电路控制多巴胺神经元的活性，并认为这些电路中的异常会产生精神分裂症的正，阴性和认知特征。谷氨酸稳态是指在兴奋性突触中及其周围谷氨酸水平的控制，我们现在有证据表明，谷氨酸稳态稳态对控制精神分裂症所涉及的电路可能很重要。谷氨酸转运蛋白控制脑谷氨酸稳态和脑中主要的谷氨酸转运蛋白是GLT-1，主要在星形胶质细胞中表达。其他人，我们发现GLT-1在兴奋性突触前末端也表达。为了了解神经元中表达的GLT-1的功能，我们生成了一个条件GLT-1基因敲除小鼠，在该小鼠中我们使用Synapsin-Cre来完成神经元中GLT-1的选择性失活。我们已经对这只小鼠进行了广泛的行为表型，包括对苯丙胺的测试反应，这些反应受兴奋性信号传导高度调节，因此，我们认为可能会受到谷氨酸植物异瘤的影响。许多小组的先前工作证明了对苯丙胺敏感性的现象，其中行为或神经元（即多巴胺释放）的影响随反复给药而增加。苯丙胺敏感性被认为是基于精神分裂症阳性症状构成的细胞过程。值得注意的是，我们发现神经元中GLT-1的失活导致急性和敏感的运动反应对苯丙胺的反应显着降低。此外，我们发现NGLT-1 KO在新颖的对象识别和浅黑色出现中的性能提高。 NOR和LDE的缺陷可能反映了工作记忆受损和焦虑的增加，精神分裂症症状的认知和负面领域的组成部分。这些观察结果使我们假设NGLT-1 KO可能表现出对与精神分裂症相关的生化和电路灾难的韧性。我们进一步假设，我们在NGLT-1 KO中观察到的表型与谷氨酸脑稳态的神经元GLT-1的区域内的环境谷氨酸的变化部分相距。我们建议进一步表征这些表型，以确定GLT-1是否可能是治疗药物发现的有效靶标。为此，我们将：1）表征接受亚基PCP给药的NGLT-1 KO小鼠的行为表型，以模拟精神分裂症中观察到的症状结构域； 2）表征NGLT-1 KO小鼠的生化表型； 3）确定GLT-1神经元基因敲除对网状细胞核切片制剂中谷氨酸稳态的影响。