Synaptic transport of endocannabinoids in the brain

项目摘要 内源性大麻素（endocannabinoid，eCB）系统在调节脑中的突触功能中起关键作用。功能障碍 eCB信号传导导致许多精神和神经障碍，包括焦虑、抑郁和抑郁症。 自闭症因此，涉及eCB功能障碍的疾病的治疗的开发需要一个新的方法。 深入了解大脑中调控eCB信号的机制。非常确定的是 突触后神经元的生理和/或病理激活导致突触后神经元的生物合成和释放。 eCB 2-花生四烯酰甘油（2-AG）。一旦释放，2-AG穿过突触间隙并激活大麻素 受体位于突触前轴突末梢，介导其行为和生理效应。 虽然在阐明2-AG信号如何控制突触功能方面已经取得了相当大的进展， 行为输出，控制突触2-AG转运的机制仍然未知，突出了一个主要的 我们对大脑中2-AG信号的基本理解存在差距。2-AG的亲脂性限制了其 通过突触扩散，表明存在促进2-AG转运的载体， 大麻素受体激活识别突触2-AG载体不仅可以大大提高我们的研究水平， 对2-AG信号传导的基本理解，但也可能导致发现新的治疗靶点 涉及eCB功能障碍的疾病。为此，我们小组最近鉴定了脂肪酸结合蛋白 （FABPs）作为eCB的细胞内载体。在这个应用程序中，我们将建立在这一进展和测试小说 由星形胶质细胞分泌的FABP 5作为2-AG信号传导所必需的突触载体发挥功能的假说 在多个大脑区域。在目标1中，我们将采用互补的药理学和遗传学方法来测试 FABP 5在抑制性和兴奋性突触中介导逆行2-AG转运的假说， 海马体和腹侧被盖区，涉及认知和情绪调节的大脑区域。在目标2中， 我们将使用我们的新型FABP 5 Flox/Flox小鼠来描述星形胶质细胞和神经元FABP 5在控制神经元凋亡中的作用。 突触2-AG转运。目的3将表征细胞内和分泌的FABP 5在细胞凋亡中的作用。 介导海马和腹侧被盖区突触的2-AG转运。成功完成本 这项提案将把FABP 5定位为2-AG在中央突触的突触载体，这将大大提高我们的研究水平。 对eCB信号传导的基本理解，并可能促进未来治疗靶向的发展 涉及eCB功能障碍的疾病。

Project Summary The endocannabinoid (eCB) system plays a key role in regulating synaptic function in the brain. Dysfunction of eCB signaling contributes to numerous psychiatric and neurological disorders including anxiety, depression, and autism. Consequently, the development of treatments for disorders involving eCB dysfunction requires a thorough understanding of the mechanisms regulating eCB signaling in the brain. It is well-established that physiological and/or pathological activation of postsynaptic neurons leads to the biosynthesis and release of the eCB 2-arachidonoylglycerol (2-AG). Once released, 2-AG traverses the synaptic cleft and activates cannabinoid receptors located on presynaptic axon terminals, which mediate its behavioral and physiological effects. Although considerable progress has been made in elucidating how 2-AG signaling controls synaptic function and behavioral outputs, the mechanism(s) governing synaptic 2-AG transport remains unknown, highlighting a major gap in our fundamental understanding of 2-AG signaling in the brain. The lipophilic nature of 2-AG limits its diffusion across the synapse, suggesting the existence of a carrier(s) that facilitates 2-AG transport to permit cannabinoid receptor activation. Identification of a synaptic 2-AG carrier would not only greatly enhance our basic understanding of 2-AG signaling but could also lead to the discovery of a new therapeutic target(s) to treat disorders involving eCB dysfunction. To that end, our group has recently identified fatty acid binding proteins (FABPs) as intracellular carriers for eCBs. In this application, we will build upon this progress and test the novel hypothesis that FABP5, secreted by astrocytes, functions as a synaptic carrier that is essential for 2-AG signaling in multiple brain areas. In Aim 1, we will employ complementary pharmacological and genetic approaches to test the hypothesis that FABP5 mediates retrograde 2-AG transport at inhibitory and excitatory synapses in the hippocampus and ventral tegmental area, brain areas involved in cognitive and emotional regulation. In Aim 2, we will employ our novel FABP5Flox/Flox mice to delineate the roles of astrocytic and neuronal FABP5 in controlling synaptic 2-AG transport. Aim 3 will characterize the contributions of intracellular and secreted FABP5 in mediating 2-AG transport at hippocampal and ventral tegmental area synapses. Successful completion of this proposal will position FABP5 as a synaptic carrier for 2-AG at central synapses, which will greatly enhance our basic understanding of eCB signaling and may facilitate the development of future therapeutics targeting disorders involving eCB dysfunction.