A Protective role for 2-AG in age-dependent cognitive impairment.

项目摘要 衰老伴随着认知能力的下降，这可以进展为认知障碍， 痴呆大麻素受体，大麻中Δ9-THC的分子靶点，调节长期和短期的 突触可塑性在许多中央突触。在年轻的小鼠和大鼠中， 受体损害记忆，而阻断发挥促认知作用。然而，相反的情况发生在 老年动物，其中大麻素受体活化增强，而遗传大麻素受体 缺失会增强与衰老相关的认知缺陷。已经提出了几种可能的机制， 解释大麻素受体信号传导如何不同地影响年轻人和老年人的认知功能 动物，但关于内源性大麻素配体如2- 花生四烯酰基-sn-甘油（2-AG）和花生四烯酰胺。在初步研究中，我们发现2-AG的产生是 与12个月大的小鼠相比，18个月和21个月大的小鼠海马体受损。基于此 发现，我们假设年龄依赖性减少2-AG动员（形成和/或失活） 会导致认知老化我们有两个特定的目标与这个假设的检验有关。目标1。 减少前脑2-AG动员对认知老化的影响。我们培育出的小鼠 前脑兴奋性神经元中的2-AG水解酶，单酰基甘油脂肪酶（MGL）（MGL-tg 小鼠）。这种基因操作降低了前脑2-AG水平，而不改变大麻素的表达。 受体或内源性大麻素相关蛋白质和脂质。此模型的独特之处在于它不显示 在缺乏产生或降解2-AG能力的基因敲除小鼠模型中观察到的补偿性变化。 使用MGL-tg小鼠，我们将询问前脑2-AG信号是否参与认知老化。我们将 比较MGL-tg和野生型小鼠（2、5、12和18月龄）的三个关键参数：研究1.1。 前脑2-AG信号传导;研究1.2.认知表现;以及，研究1.3。神经炎症的标志物。 目标2.增强前脑2-AG动员对认知老化的影响。如果2-AG信号减少， 有助于认知老化，那么这种缺陷的药物纠正应该改善老年人的认知。 动物我们将确定是否亚慢性口服给药的化合物NF 1819，一种新的MGL 具有良好药物样特性的抑制剂，改善MGL-tg和野生型中与年龄相关的认知缺陷 小鼠在第一个实验（研究2.1）中，我们将确定NF 1819的最佳剂量，并在随后的实验中， 在一个实验（研究2.2）中，我们将向MGL-tg小鼠和野生型小鼠施用NF 1819 30天或90天 控制，测试认知能力和神经炎症标志物。该项目有可能 揭示2-AG信号在衰老大脑中的新功能，并为发现 缓解与年龄相关的认知缺陷的新策略。

PROJECT SUMMARY Aging is accompanied by a decrease in cognitive ability, which can progress into cognitive impairment and dementia. Cannabinoid receptors, the molecular target of Δ9-THC in marijuana, modulate long- and short-term synaptic plasticity at many central synapses. In young mice and rats, pharmacological activation of these receptors impairs memory, whereas blockade exerts pro-cognitive effects. The opposite occurs, however, in aged animals, in which cannabinoid receptor activation alleviates, whereas genetic cannabinoid receptor deletion enhances, aging-related cognitive deficits. Several possible mechanisms have been proposed to explain how cannabinoid receptor signaling might differentially influence cognitive function in young and old animals, but very limited data are available about the role played by endocannabinoid ligands such as 2- arachidonoyl-sn-glycerol (2-AG) and anandamide. In preliminary studies, we found that 2-AG production is impaired in the hippocampus of 18- and 21-month old mice, compared to 12-month old mice. Based on this finding, we hypothesize that age-dependent reductions in 2-AG mobilization (formation and/or deactivation) contribute to cognitive aging. We have two Specific Aims that are relevant to a test of this hypothesis. Aim 1. Effects of reduced forebrain 2-AG mobilization on cognitive aging. We have generated mice that overexpress the 2-AG-hydrolyzing enzyme, monoacylglycerol lipase (MGL), in excitatory neurons of the forebrain (MGL-tg mice). This genetic manipulation reduces forebrain 2-AG levels without altering expression of cannabinoid receptors or endocannabinoid-related proteins and lipids. This model is unique in that it does not display the compensatory changes seen in knock-out mouse models that lack the ability to produce or degrade 2-AG. Using MGL-tg mice, we will ask whether forebrain 2-AG signaling is involved in cognitive aging. We will compare MGL-tg and wild-type mice – aged 2 , 5, 12 and 18 months – for three key parameters: Study 1.1. Forebrain 2-AG signaling; Study 1.2. Cognitive performance; and, Study 1.3. Markers of neural inflammation. Aim 2. Effects of enhanced forebrain 2-AG mobilization on cognitive aging. If decreased 2-AG signaling contributes to cognitive aging, then pharmacological correction of this deficit should ameliorate cognition in old animals. We will determine whether subchronic oral administration of the compound NF1819, a novel MGL inhibitor with favorable drug-like properties, improves age-related cognitive deficits in MGL-tg and wild-type mice. In a first experiment (Study 2.1), we will determine the optimal dosing of NF1819, and in a subsequent experiment (Study 2.2), we will administer NF1819 for 30 days or 90 days to MGL-tg mice and wild-type controls, testing cognitive performance and neuroinflammatory markers. The project has the potential to uncover new functions of 2-AG signaling in the aging brain, and to lay the groundwork for the discovery of novel strategies to alleviate age-related cognitive deficits.