Retrograde Signaling by Endogenous Cannabinoids

描述（由申请人提供）：最近发现，神经元可以从其细胞体和树突释放内源性大麻素（eCB），以激活突触前1型大麻素受体（CB1R）。尽管深入研究，但关于eCB信号传导的许多基本问题仍然没有答案。已经表明，eCB可以暂时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释放是否允许细胞在生理条件下全局调节所有突触？eCB信号传导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化，以调节联合可塑性的时间和频率依赖性？eCB是否允许突触的靶依赖性调节？eCB信号是如何调制的？先前的研究也表明，突触前CB1R控制小脑中突触后形式的长期抑制（LTD）的诱导，这在运动学习中起着重要作用。CB1R如何控制这种形式的LTD？eCB释放的特性是否导致了适合运动学习的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eCB信号传导的这一方面比突触调节少得多。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，而其他细胞只受邻近细胞释放的eCB的影响？为什么eCB会导致某些细胞类型的兴奋性发生持续变化，而对其他细胞只产生短暂影响？ 这些问题将通过研究大鼠和小鼠脑切片中的eCB信号来解决。研究将使用全细胞电压钳和电流钳记录来诱发eCB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，这是一个重要的调节eCB释放，将被测量和操纵。突触前钙离子进入，这是由CB1R激活调节的定量，将提供一个衡量eCB介导的突触前调制，并将使我们能够研究个别的突触前细胞。本研究所需的几乎所有技术都在实验室中常规使用，因此拟议的实验可能会在规定的时间内完成。 这些研究将导致更深入地了解eCB信号在小脑，运动控制和运动学习中的作用。他们还将提供对eCB信号传导的一般见解，这将有助于理解疼痛，癫痫，食欲控制，抑郁症和帕金森病。

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.