Targeting cotransmission for circuit-specific pharmacotherapy

与大多数中枢神经系统突触一样，多巴胺神经元突触释放不止一种神经递质， 从发育到营养支持再到更细微的信号传递的作用。多巴胺神经元 释放谷氨酸作为协传递体。谷氨酸的共同传递给了 多巴胺神经元在纹状体中跨其主要靶神经元的突触作用。回火 条件还原谷氨酸合成酶实现多巴胺神经元谷氨酸共传递 由GLS1编码的谷氨酰胺酶在时相放电时减少多巴胺神经元谷氨酸的共传递 频率。具有GLS1全局杂合性降低的小鼠表现出增强的潜在抑制，并 精神刺激剂敏感度较低，涉及异常显著归因的两种行为效应。 令人惊讶的是，这两种表型在GLS1降低受限于其多巴胺的小鼠中可见 神经元。GLS1减少对多巴胺神经元依赖行为的影响与 精神分裂症的症状，为治疗潜力辩解。减少的微妙，影响 伏核中多巴胺神经元谷氨酸在时相放电频率下的共同传递， 确定显著属性中涉及的关键电路。这项提议的驱动力假设是 多巴胺神经元谷氨酸共传递参与突显的归因和减少 共传播对于精神分裂症的药物治疗具有潜在的治疗潜力。在这个项目中，我们将 首先关注GLS1降低对多巴胺神经元、多巴胺和谷氨酸的突触影响 释放(目标1)，记录在对两种递质都有反应的胆碱能中间神经元和纹状体 多巴胺门控氯通道的表达使投射神经元成为多巴胺生物传感器 LGC-53，可以比较GLS1降低对DA和GLU信号的差异影响。然后, 使用INTRSECT策略(目标2)，我们将确定纹状体多巴胺神经元的投射能够 谷氨酸协同传递，并使用光遗传刺激来研究它们在显著归因中的作用。 最后，我们将测试谷氨酰胺酶抑制药物疗法(目标3)，首先在脑片上显示基因 GLS1的降低和谷氨酰胺酶的药理抑制同样优先产生影响 多巴胺神经元谷氨酸共传递，然后在成年期模型中诱导全局GLS1减少 药物治疗以显示对行为的影响。最后，我们将制造一种多巴胺神经元选择性GLS1 成年期的减少以评估突触和行为的影响。这项研究应该增加 多巴胺神经元谷氨酸共传递作用的认识及治疗进展 关于谷氨酸释放的活性依赖性调节，特别是谷氨酰胺酶抑制作为一种新的 精神分裂症的药物治疗。

Dopamine neuron synapses — like most CNS synapses — release more than one neurotransmitter, with roles that extend from development, to trophic support to more nuanced signaling. Dopamine neurons release glutamate as a cotransmitter. Glutamate cotransmission confers striking heterogeneity to the synaptic actions of dopamine neurons across their principal target neurons in the striatum. Tempering dopamine neuron glutamate cotransmission by conditional reduction of the glutamate synthesizing enzyme glutaminase, encoded by Gls1, reduces dopamine neuron glutamate cotransmission at phasic firing frequencies. Mice with a global heterozygous reduction of Gls1 show potentiated latent inhibition, and are less prone to psychostimulant sensitization, two behavioral effects involving aberrant salience attribution. Strikingly, these two phenotypes are seen in mice with a Gls1 reduction restricted to their dopamine neurons. The impact of the Gls1 reduction on dopamine neuron dependent behaviors runs counter to symptoms of schizophrenia, arguing for therapeutic potential. The subtlety of the reduction, affecting dopamine neuron glutamate cotransmission at phasic firing frequencies in the nucleus accumbens, identifies key circuitry involved in salience attribution. The driving hypothesis of this proposal is that dopamine neuron glutamate cotransmission is involved in salience attribution and that reducing cotransmission has therapeutic potential for schizophrenia pharmacotherapy. In this project, we will focus first on the synaptic impact of the Gls1 reduction on dopamine neuron dopamine and glutamate release (Aim 1), recording in cholinergic interneurons that respond to both transmitters, and in striatal projection neurons made into dopamine biosensors by expression of the dopamine-gated chloride channel LGC-53, enabling comparison of the differential impact of the Gls1 reduction on DA and GLU signals. Then, using an INTRSECT strategy (Aim 2), we will identify striatal dopamine neuron projections capable of glutamate cotransmission, and use optogenetic stimulation to examine their role in salience attribution. Finally, we will test glutaminase inhibition pharmacotherapy (Aim 3) showing first in brain slices that genetic reduction of Gls1 and pharmacological inhibition of glutaminase similarly and preferentially impact dopamine neuron glutamate cotransmission, and then induce a global Gls1 reduction in adulthood modeling pharmacotherapy to show the behavioral impact. Finally, we will make a dopamine neuron-selective Gls1 reduction in adulthood to evaluate both the synaptic and behavioral impact. This research should increase understanding of the role of dopamine neuron glutamate cotransmission and advance therapeutics based on activity dependent modulation of glutamate release, specifically glutaminase inhibition as a novel pharmacotherapy for schizophrenia.