Developing a zebrafish model of neurovascular coupling (NVC)

大脑的血液供应受到一种叫做“神经血管耦合”的过程的严格控制。这增加了大脑活跃区域的血液供应，尽管这是如何实现的还不完全清楚。神经血管耦合在中风和痴呆等疾病中存在缺陷，了解这一过程可能最终导致改善这些疾病的策略。由于神经血管耦合目前只能在血液供应完整的活体大脑中进行研究，因此研究需要使用动物，通常是小鼠和大鼠。这些实验需要手术来暴露大脑，并在清醒和受约束或麻醉的动物身上进行大脑成像，这不可避免地会引起痛苦和痛苦。因此，我们希望开发一种模型，可以提供科学的洞察神经血管耦合，但减少侵入性动物实验的数量。斑马鱼在研究神经血管耦合方面有两个关键优势。首先，因为大脑是透明的，我们可以培育出“转基因”动物，其中某些细胞发出不同颜色的荧光，我们可以在没有任何仪器的情况下对大脑进行成像。其次，我们可以在动物不死亡的情况下停止心脏，因为它从周围的水中获得足够的氧气。小斑马鱼胚胎在超过5天之前不被认为是自由生活的动物，使用这些胚胎不被政府立法视为动物实验（称为非保护）。我们将利用这些优势，在无保护的斑马鱼胚胎中建立神经血管偶联模型。我们培育了转基因斑马鱼，当细胞中的钙含量增加时，它们的血管或神经就会发出明亮的荧光。由于钙含量在被“激活”的细胞中增加，这些转基因细胞系使我们能够描绘出大脑的哪些部分在对光或声音等刺激做出反应时被激活。然后，我们可以测量大脑不同部位对这种刺激的血流量，并进行实验来测试这种反应是否受到某些药物或环境变化（如二氧化碳水平升高或血流量改变）的影响。如果我们发现斑马鱼的神经血管耦合存在并以与哺乳动物相同的方式受到控制，我们的新模型将能够取代受保护动物的使用，并为神经血管耦合提供新的科学见解。

The blood supply to the brain is tightly controlled by a process called "neurovascular coupling". This increases blood supply to areas of the brain which are active, although how this is achieved is not completely understood. Neurovascular coupling is defective in conditions such as stroke and dementia, and understanding this process might ultimately lead to strategies to improve these diseases.Because neurovascular coupling can currently only be studied in a living brain with an intact blood supply, its study requires the use of animals, commonly mice and rats. These experiments require surgery to expose the brain, and imaging of the brain in animals that are either awake and restrained, or anaesthetised, which inevitably induces distress and suffering. We therefore wish to develop a model that can provide scientific insight into neurovascular coupling but reduces the number of invasive animal experiments.The zebrafish has two key advantages for the study of neurovascular coupling. Firstly, because it is transparent and we can generate "transgenic" animals in which certain cells fluoresce different colours, we can image the brain without any instrumentation. Secondly, we can stop the heart without the animal dying, as it obtains sufficient oxygen from the water surrounding it. The tiny zebrafish embryo is not considered to be a free living animal until it is older than 5d, and using these is not considered to be an animal experiment by government legislation (called non-protected).We will exploit these advantages to develop a model of neurovascular coupling in non-protected zebrafish embryos. We have generated genetically modified zebrafish in which either the blood vessels or the nerves fluoresce brightly when levels of calcium in these cells increase. Because calcium levels increase in cells that are "activated", these transgenic lines allow us to image which parts of the brain are activated in response to a stimulus such as light or sound. We can then measure blood flow in different parts of the brain in response to this stimulus, and perform experiments to test whether this response is affected by certain drugs or alterations in conditions such as increased levels of carbon dioxide or alteration in blood flow.If we find that neurovascular coupling exists and is controlled in the same ways in zebrafish as in mammals, our new model would be able to replace the use of protected animals and to provide new scientific insights into neurovascular coupling.