Retrograde Signaling by Endogenous Cannabinoids

描述(申请人提供)：最近发现神经元可以从细胞体和树突释放内源性大麻素(ECB)来激活突触前1型大麻素受体(CB1Rs)。尽管进行了深入的研究，但有关欧洲央行信号传递的许多基本问题仍未得到解答。已有研究表明，ECB可以一过性地降低神经递质释放的可能性，但这种短期可塑性的生理作用是什么？ECB的释放是否允许细胞在生理条件下对所有突触进行全局调节？ECB信号是否为短期联合突触可塑性提供了一般机制？ECB的释放是否在不同的细胞类型中专门调节联合可塑性的时间和频率依赖性？ECB允许靶点依赖的突触调节吗？欧洲央行的信号是如何调制的？以前的研究也表明，突触前CB1Rs控制着小脑中突触后形式的长期抑郁(LTD)的诱导，这在运动学习中发挥着重要作用。CB1R如何控制这种形式的有限公司？ECB释放的特性是否导致了适合于运动学习的LTD诱导的时间依赖性？ECB还可以调节某些类型细胞的兴奋性，尽管与突触调节相比，ECB信号在这方面的研究要少得多。ECB是否调节整个大脑细胞的神经元兴奋性，或者这是一种罕见的信号形式？为什么ECB允许一些细胞调节自己的兴奋性，而另一些细胞只受到邻近细胞释放的ECB的影响？为什么ECB导致某些细胞类型的兴奋性持续变化，而只对其他细胞产生短暂影响？ 这些问题将通过研究大鼠和小鼠脑片中的ECB信号来解决。研究将使用全细胞电压钳和电流钳记录来激发ECB的释放，量化突触强度的变化，监测放电特性，并测量对膜电位的影响。突触后钙是ECB释放的重要调节因素，将被测量和操纵。突触前钙内流的定量受CB1R激活的调节，将为ECB介导的突触前调制提供一种测量方法，并将使我们能够研究单个突触前细胞。这项研究中需要的几乎所有技术都是实验室常规使用的，因此拟议的实验很可能会在分配的时间内完成。 这些研究将加深对欧洲央行信号在小脑、运动控制和运动学习中的作用的理解。他们还将提供对欧洲央行信号的总体洞察，这将有助于理解疼痛、癫痫、食欲控制、抑郁和帕金森氏症。

DESCRIPTION (provided by applicant): It was recently discovered that neurons can release endocannabinoids (eCBs) from their cell bodies and dendrites to activate presynaptic type 1 cannabinoid receptors (CB1Rs). Despite intensive study many fundamental questions about eCB signaling remain unanswered. It has been shown that eCBs can transiently decrease the probability of neurotransmitter release, but what is the physiological role of such short term plasticity? Does eCB release allow cells to globally regulate all of their synapses under physiological conditions? Does eCB signaling provide a general mechanism for short-term associative synaptic plasticity? Is eCB release specialized in different cell types to regulate the timing and frequency dependence of associative plasticity? Do eCBs allow target-dependent regulation of synapses? How is eCB signaling modulated? Previous studies have also shown that presynaptic CB1Rs control the induction of a postsynaptic form of long-term depression (LTD) in the cerebellum that plays an important role in motor learning. How do CB1Rs control this form of LTD? Do the properties of eCB release lead to a timing dependence for the induction of LTD that is suited to motor learning? eCBs can also regulate the excitability of some types of cells, although this aspect of eCB signaling is much less studied than synaptic regulation. Do eCBs regulate neuronal excitability for cells throughout the brain or is this a rare form of signaling? Why do eCBs allow some cells to regulate their own excitability whereas others are only influenced by eCBs released from neighboring cells? Why do eCBs lead to sustained changes in excitability in some cell types and only transiently affect others? These questions will be addressed by studying eCB signaling in brain slices from rats and mice. Studies will use whole-cell voltage clamp and current-clamp recordings to evoke eCB release, quantify changes in synaptic strength, monitor firing properties and measure effects on membrane potential. Postsynaptic calcium, which is a vital regulator of eCB release, will be measured and manipulated. Quantification of presynaptic calcium entry, which is regulated by CB1R activation, will provide a measure of eCB-mediated presynpatic modulation and will allow us to study individual presynaptic cells. Virtually all of the techniques required in this study are routinely used in the laboratory, making it likely that the proposed experiments will be completed in the allocated time. These studies will lead to a deeper understanding of the role of eCB signalling in the cerebellum, motor control and motor learning. They will also provide general insight into eCB signaling that will aid in the understanding of pain, epilepsy, appetite control, depression and Parkinson's disease.