Bioenergetic role of astrocytes in neuronal plasticity and behaviour

星形胶质细胞在突触功能中发挥积极作用，以各种方式调节神经传递，包括神经元活动的代谢支持。星形胶质细胞是唯一能够储存能量的脑细胞，这些细胞内储存有糖原。这种能量库可以响应神经元活动的变化而迅速动员，并已被证明在细胞水平上影响突触可塑性，调节体内学习，记忆和决策。 尽管有大量的证据描述了星形胶质细胞到神经元L-乳酸穿梭的关键作用，但也有实验证据破坏了这项工作。事实上，也已经证明，神经元可以依靠它们自己的糖酵解来产生能量，并且不需要星形胶质细胞将葡萄糖“预处理”成L-乳酸。这些相反的意见导致了这一领域的激烈辩论，这一问题仍未得到解决。在这个建议中，我们的目标是实验解剖星形胶质细胞L-乳酸在突触传递，可塑性和行为的不同方面的影响。 我们将结合不同的分子，功能和成像方法进行详细的调查，这是严重缺乏在这一领域。我的研究计划将分为三个不同的目标：1.我们将研究不同形式的突触传递和可塑性对星形胶质细胞到神经元L-乳酸穿梭的依赖性。这将使用针对神经元和星形胶质细胞的膜片钳电生理学和药理学来实现，以具体确定不同形式的短期和长期可塑性是否需要来自星形胶质细胞的L-乳酸。 2.利用L-乳酸基因荧光传感器的双光子成像技术研究星形胶质细胞-神经元L-乳酸穿梭的时空动力学。这些传感器将使用细胞特异性启动子病毒靶向神经元或星形胶质细胞，并且将量化响应于突触刺激的细胞外L-乳酸的变化。3.我们将研究星形胶质细胞到神经元乳酸穿梭在不同行为中的作用，比较学习行为和先天行为。它们的不同之处在于，习得行为需要反复的接触和训练，已知可以唤起长期的突触可塑性和记忆形成，而先天行为，如对捕食者的反应，不需要训练或学习。 观点：这项工作将使我们能够解开星形胶质细胞神经元L-乳酸穿梭的复杂性，定义L-乳酸依赖和独立的突触和行为过程。我们的详细研究将代表星形胶质细胞-神经元代谢偶联领域的重大进展，进一步阐明这一生物学过程的复杂性，并解决这一领域长期存在的争论。

Astrocytes play active roles in synaptic function, regulating neurotransmission in various means including metabolic support of neuronal activity. Astrocytes are the only brain cell capable of energy storage, which is stocked as glycogen inside these cells. This energy reservoir can be rapidly mobilised in response to changes in neuronal activity and has been shown to influence synaptic plasticity on the cellular level, regulating learning, memory, and decision making in vivo. Despite abundant evidence describing a critical role of the astrocyte to neuron L-lactate shuttle, there is also experimental evidence undermining this work. Indeed, it has also been demonstrated that neurons can rely on their own glycolysis for energy production and do not require `pre-processing' of glucose into L-lactate by astrocytes. These opposing observations have led to heated debate in this field, which remains unresolved. In this proposal we aim to experimentally dissect the influence of astrocyte L-lactate in distinct aspects of synaptic transmission, plasticity, and behaviour. We will carry out a detailed investigation combining distinct molecular, functional, and imaging approaches, which is severely lacking in this domain. My research program will be divided into three distinct aims; 1.We will investigate the dependence of distinct forms of synaptic transmission and plasticity on the astrocyte to neuron L-lactate shuttle. This will be achieved using patch clamp electrophysiology and pharmacology targeting both neurons and astrocytes to determine specifically whether distinct forms of short and long-term plasticity require L-lactate from astrocytes. 2.We will determine the spatiotemporal dynamics of the astrocyte to neuron L-lactate shuttle using two-photon imaging of genetically encoded fluorescent sensors for L-lactate. These sensors will be virally targeted to neurons or astrocytes using cell-specific promoters, and changes in extracellular L-lactate in response to synaptic stimulation will be quantified. 3.We will examine the role of astrocyte to neuron lactate shuttle in distinct behaviours comparing learned versus innate behaviours. These are distinct in that learned behaviours require repeated exposure and training, known to evoke long-term synaptic plasticity and memory formation, whereas innate behaviours, such as response to predator, do not require training or learning. Perspectives: This work will allow us to unravel the complexities of the astrocyte-neuron L-lactate shuttle, defining L-lactate-dependent and -independent synaptic and behavioural processes. Our detailed investigation will represent a significant advancement in the field of astrocyte-neuron metabolic coupling, shedding further light on the complexity of this biological process and resolving a long-standing debate in this field.