Physiological roles of 2-arachidonoylglycerol, an endogenous cannabinoid receptor ligand

我们发现，在表达大麻素CB2受体的HL-60细胞中，2-花生四烯醇甘油酯（2- ag）诱导细胞内游离Ca^<2+>浓度的快速瞬时增加。然后详细研究了2-AG与其他大麻素受体配体的构效关系。我们发现2-AG的醚连接类似物具有显著的生物活性，这表明2-AG本身的结构，而不是其代谢物，实际上被CB2受体分子识别。值得注意的是，2-AG的醚键类似物和酰胺键类似物的活性明显低于2-AG，这表明酯键的存在对于表现出强大的激动活性至关重要。与2-AG相反，anandamide被发现作为CB2受体的弱部分激动剂。大麻的主要成分Δ^9-四氢大麻酚的活性也很低。我们进一步研究了各种2-A…More G类似物以及经典大麻素和合成大麻素的活性。含有各种饱和脂肪酸、单烯脂肪酸和二烯脂肪酸的单酰基甘油活性很低。2-AG是CB2受体最有效的激动剂之一。我们得出结论，CB2受体最初是2-AG受体，Δ^9-四氢大麻酚可能干扰2-AG的作用，从而引发各种药理作用。然后我们检测了大脑中2-AG的水平。大鼠脑组织中2-AG含量为0.23 nmol/g。我们发现，在给药的大鼠脑和断头后缺血大鼠脑中，2-AG水平明显升高。我们还发现，在Ca^<2+>存在的条件下，脑匀浆产生了大量的2- ag。我们证实2-AG可以由肌醇磷脂通过磷脂酶C和随后的二酰基甘油脂肪酶活性的作用产生；大麻素受体的功能似乎很可能与肌醇磷脂代谢的增加密切相关。刺激后脑内迅速生成的2-AG在调节神经传递中起着重要的生理作用。少

We found that 2-arachidonoylglycerol (2-AG) induces rapid transient increases in intracellular free Ca^<2+> concentrations in HL-60 cells which express the cannabinoid CB2 receptor. We then examined the structure-activity relationship of 2-AG and other cannabinoid receptor ligands in detail. We found that an ether-linked analogue of 2-AG possesses significant biological activity, indicating that the structure of 2-AG itself, but not its metabolite, is actually recognized by the CB2 receptor molecule. Noticeably, the activities of ether-linked analogues and amide bond-containing analogues of 2-AG were considerably lower than that of 2-AG, suggesting that the presence of an ester linkage is crucially important for exhibiting strong agonistic activity. In contrast to 2-AG, anandamide was found to act as a weak partial agonist toward the CB2 receptor. The activity of Δ^9-tetrahydrocannabinol, at major constituent of marijuana, was also low. We further examined the activities of various 2-A … More G analogues and classical and synthetic cannabinoids. The activities of monoacylglycerols containing various saturated, monoenoic and dienoic fatty acids were very low. 2-AG acted as one of the most potent agonists toward the CB2 receptor. We concluded the CB2 receptor is originally a 2-AG receptor, and that Δ^9-tetrahydrocannabinol may interfere with the actions of 2-AG thereby eliciting various pharmacological effects. We then examined the level of 2-AG in the brain. Rat brain was found to contain 0.23 nmol/g tissue of 2-AG.We found that the level of 2-AG was elevated markedly in picrotoxinin-administered rat brain and in post-decapitative ischemic rat brain. We also found that a large amount of 2-AG was generated when brain homogenate was incubated in the presence of Ca^<2+>. We confirmed that 2-AG can be generated from inositol phospholipids through the action of phospholipase C and subsequent diacylglycerol lipase activity ; it seems very likely that the function of the cannabinoid receptors are closely related to increased inositol phospholipid metabolism. 2-AG rapidly generated in the brain after stimulation mat play important physiological roles in the regulation of neurotransmission. Less