CB1R independent effects of cannabinoids on synaptic physiology in the CNS.

描述（由申请人提供）：这是一项基础科学提案，旨在使用体外电生理和光学技术来进一步了解我的实验室发现的一种极其不寻常的大麻素依赖信号形式。具体来说，我们已经观察到大麻素受体激动剂通过大麻素I型（CB1）受体独立机制增强齿状回中GABA的动作电位独立释放。尽管近年来已经带来了大量关于内源性大麻素在中枢神经系统生理中的特定作用的新信息，但我们发现的大麻素受体激动剂的作用在许多方面似乎是独一无二的。首先，它不依赖于CB1、CB2或香草素I型受体的激活，并且仍然存在于CB1-/-动物中。第二，它明确调节动作电位独立的胞吐事件，而不改变动作电位依赖的事件；第三，它最终导致胞吐的促进（而不是抑制）。虽然我们的初步数据代表了大麻素在中枢神经系统生理学中的新作用的重大进展，但关于这一新现象的许多基本问题仍然存在。因此，本提案要求资金通过实施两个具体目标来继续我们在这一领域的调查。目的1将测试大麻素介导的动作电位独立胞吐的促进作用取决于与尚未确定的GPCR的特定配体受体相互作用的假设。具体来说，我们假设G1s -> AC -> cAMP -> PKA信号级联参与其中。目的2将验证anandamide或其代谢物之一将是促进动作电位独立释放的最有效内源性配体的假设，并且最佳激动剂将在生理相关的浓度范围内发挥良好作用。总的来说，这些目标旨在提供有可能明确确定我们的发现对大麻素领域的重要性的数据，这将直接促进对这一现象的长期和更大规模的调查。

DESCRIPTION (provided by applicant): This is a basic science proposal designed to use in vitro electrophysiological and optical techniques to further our understanding of an extremely unusual form of cannabinoid dependent signaling discovered in my lab. Specifically, we have observed that cannabinoid receptor agonists potentiate action potential independent release of GABA in the dentate gyrus through a cannabinoid type I (CB1) receptor independent mechanism. Although recent years have brought an enormous wealth of new information about the specific roles of endogenous cannabinoids in CNS physiology, the effect of cannabinoid receptor agonists that we have discovered appears to be unique in numerous respects. First, it does not depend on activation of CB1, CB2, or vanilloid type I receptors, and is still present in CB1-/- animals. Second, it clearly modulates action potential independent exocytotic events without altering action potential dependent events, and third, it ultimately results in the facilitation (rather than inhibition) of exocytosis. While our preliminary data represent significant progress towards characterizing a new role for cannabinoids in CNS physiology, many fundamental questions regarding this new phenomenon remain. Therefore this proposal requests funds to continue our investigation in this area through implementation of two Specific Aims. Aim 1 will test the hypothesis that cannabinoid mediated facilitation of action potential independent exocytosis depends on a specific ligand receptor interaction with an as yet unidentified GPCR. Specifically, we hypothesize that a G1s -> AC -> cAMP -> PKA signaling cascade is involved. Aim 2 will test the hypothesis that anandamide or one of its metabolites will be the most effective endogenously available ligand for facilitation of action potential independent release, and that the best agonists will work well within a physiologically relevant concentration range. Collectively, these Aims are designed to provide data that have the potential to clearly establish the significance of our findings for the cannabinoid field, and that will directly facilitate a longer term and larger scale investigation of the phenomenon. PUBLIC HEALTH RELEVANCE: Nearly all the known central effects of endogenous cannabinoids are thought to be mediated by activation of a single type of receptor, the CB1 cannabinoid receptor. We have recently discovered a highly novel form of cannabinoid mediated signaling that does not depend on CB1 receptor activation, and that has unique effects on CNS physiology. The current proposal is designed to address several fundamental questions about this new signaling system that we hope will ultimately establish the overall significance (and potential) of the finding.