Dissecting populations of PrRP neurone in conditional transgenic mice

为了生存，我们需要平衡我们的能量摄入（我们吃的食物）和代谢需求。后者包括我们保暖、锻炼和维持身体机能所需的能量。我们必须确保有足够的能量以葡萄糖的形式容易获得，并以脂肪的形式储存，并预测需求的任何变化。为了做到这一点，大脑，特别是下丘脑和脑干的区域，从其他器官收集信息，关于我们最近是否吃过东西，一天中的时间，我们血液中的葡萄糖含量以及脂肪组织中储存了多少脂肪。所有这些信息都被特定的脑细胞整合并转化为行动，再一次被外围器官转化为行动：我们是否应该吃东西，产生更多的热量，从储存中释放更多的能量？我们的问题是，我们对执行这一关键综合功能的脑细胞（神经元）种类知之甚少。然而，我们已经证明了一种名为PrRP的新型大脑递质能够调节许多对能量需求变化的关键反应，并且缺乏PrRP受体的小鼠是肥胖的。更有趣的是，PrRP是在上述下丘脑和脑干的特定区域的不同神经元群中产生的。然而，问题仍然是如何在不同的环境中研究或操纵这些不同的神经元。我们有一个独特的机会，将最好的生理和行为分析与尖端的遗传学结合在一起。利用最新的技术，我们将生产出对PrRP神经元中表达的基因进行无害改变的转基因小鼠。第一种老鼠将只在PrRP神经元中表达荧光标记物，这将使我们能够在大脑中数百万个细胞中看到它们。然后，我们将能够记录他们的电活动，并确定他们对不同刺激的反应。这只老鼠也将允许我们选择性地沉默信号分子，从而证明不同信号对PrRP神经元的重要性。第二只老鼠将在PrRP基因中插入一小段DNA，以破坏其表达。我们预测这只老鼠会肥胖，因为它不能对代谢信号做出反应，产生正常的调节反应。然而，我们可以将这只小鼠与其他小鼠杂交，这将导致PrRP基因在特定PrRP神经元群体中的插入物被移除。这将使我们能够对老鼠进行研究，这些老鼠的PrRP现在仅在脑干中正常运作，然后在下丘脑也正常运作。通过这些研究，我们将对控制能量平衡的大脑回路获得重要的见解，这可能使我们能够制定新的策略来对抗迅速发展的肥胖流行病。

In order to survive, we need to balance our energy intake (the food we eat) with metabolic demands. The latter includes the energy we require to keep warm, exercise and maintain body functions. We must ensure that there is adequate energy easily available in the form of glucose and stored in the form of fat, and predict any changes in demand. To do this, the brain and particularly regions of the hypothalamus and brainstem, collect information from other organs regarding whether we have recently eaten, the time of day, how much glucose is in our blood and how much fat is laid down in adipose tissue. All of this information is integrated by specific brain cells and translated into actions, again by peripheral organs: should we eat, produce more warmth, release more energy from stores? Our problem is that we know relatively little about the kinds of brain cell (neurone) which carry out this key integrative function. However, we have demonstrated that a novel brain transmitter, called PrRP, is capable of regulating many of these critical responses to changing energy demands, and that mice lacking the receptor for PrRP are obese. More interestingly, PrRP is produced in distinct populations of neurone in the exact regions of the hypothalamus and brainstem mentioned. However, the problem remains how to study or manipulate these distinct neurones in their different environments. We have a unique opportunity to bring together the very best physiological and behavioural analyses with cutting-edge genetics. Using the latest techniques we will produce transgenic mice with harmless alterations to the genes expressed in PrRP neurones. The first type of mouse will express a fluorescent marker only in PrRP neurones which will allow us to visualise them amongst the millions of cells in the brain. We will then be able to record their electrical activity and determine how they respond to different stimuli. This mouse will also allow us to selectively silence signalling molecules, thus demonstrating the importance of different signals specifically to PrRP neurones. The second mouse will have a small piece of DNA inserted into the PrRP gene to disrupt its expression. We predict that this mouse will be obese because it cannot respond to metabolic signals to produce the normal regulatory responses. However, we can cross this mouse with others which will result in the insert being removed from the PrRP gene in specific populations of PrRP neurone. This will allow us to study mice in which PrRP now functions normally in the brainstem alone and then also in the hypothalamus. Through these studies we will gain important insight into the brain circuitry controlling energy balance and that will perhaps allow us to develop new strategies to fight the burgeoning obesity epidemic.