Bioenergetic role of astrocytes in neuronal plasticity and behaviour

星形胶质细胞在突触功能中发挥着积极的作用，通过多种方式调节神经传递，包括代谢支持神经元的活动。星形胶质细胞是唯一能够储存能量的脑细胞，能量以糖原的形式储存在这些细胞中。这种能量储存库可以迅速动员起来，以应对神经元活动的变化，并已被证明在细胞水平上影响突触的可塑性，调节体内的学习、记忆和决策。尽管有大量证据表明星形胶质细胞在神经元L-乳酸穿梭中起着关键作用，但也有实验证据破坏了这一工作。事实上，也已经证明，神经元可以依靠自己的糖酵解来产生能量，而不需要星形胶质细胞将葡萄糖‘预处理’为L-乳酸。这些截然相反的观点在这一领域引发了激烈的辩论，至今仍未解决。在这项提案中，我们的目标是通过实验剖析星形胶质细胞L-乳酸在突触传递、可塑性和行为方面的影响。我们将结合不同的分子、功能和成像方法进行详细的研究，这在这个领域是严重缺乏的。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对神经元L-乳酸穿梭的依赖。这将通过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星形胶质细胞的L乳酸。2.我们将利用基因编码的L-乳酸荧光传感器的双光子成像技术来确定星形胶质细胞到神经元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通过病毒靶向神经元或星形胶质细胞，并将量化细胞外L-乳酸对突触刺激的反应。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，比较后天行为和先天行为。这些不同之处在于，后天习得的行为需要反复暴露和训练，已知可以唤起长期的突触可塑性和记忆形成，而天生的行为，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依赖和不依赖乳酸的突触和行为过程。我们的详细研究将代表着星形胶质细胞-神经元代谢偶联领域的重大进展，进一步揭示这一生物学过程的复杂性，并解决该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.