Leishman Emma, Mackie Ken, Luquet Serge, Bradshaw Heather B
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA.
Department of Psychological and Brain Sciences, Indiana University, Bloomington, IN, USA; Gill Center for Biomolecular Neuroscience, Indiana University, Bloomington, IN, USA.
Biochim Biophys Acta. 2016 Jun;1861(6):491-500. doi: 10.1016/j.bbalip.2016.03.003. Epub 2016 Mar 5.
A leading hypothesis of N-acyl ethanolamine (NAE) biosynthesis, including the endogenous cannabinoid anandamide (AEA), is that it depends on hydrolysis of N-acyl-phosphatidylethanolamines (NAPE) by a NAPE-specific phospholipase D (NAPE-PLD). Thus, deletion of NAPE-PLD should attenuate NAE levels. Previous analyses of two different NAPE-PLD knockout (KO) strains produced contradictory data on the importance of NAPE-PLD to AEA biosynthesis. Here, we examine this hypothesis with a strain of NAPE-PLD KO mice whose lipidome is uncharacterized. Using HPLC/MS/MS, over 70 lipids, including the AEA metabolite, N-arachidonoyl glycine (NAGly), the endocannabinoid 2-arachidonyl glycerol (2-AG) and prostaglandins (PGE(2) and PGF(2α)), and over 60 lipoamines were analyzed in 8 brain regions of KO and wild-type (WT) mice. Lipidomics analysis of this third NAPE-PLD KO strain shows a broad range of lipids that were differentially affected by lipid species and brain region. Importantly, all 6 NAEs measured were significantly reduced, though the magnitude of the effect varied by fatty acid saturation length and brain region. 2-AG levels were only impacted in the brainstem, where levels were significantly increased in KO mice. Correspondingly, levels of arachidonic acid were significantly decreased exclusively in brainstem. NAGly levels were significantly increased in 4 brain regions and levels of PGE(2) increased in 6 of 8 brain regions in KO mice. These data indicate that deletion of NAPE-PLD has far broader effects on the lipidome than previously recognized. Therefore, behavioral characteristics of suppressing NAPE-PLD activity may be due to a myriad of effects on lipids and not simply due to reduced AEA biosynthesis.
关于N-酰基乙醇胺(NAE)生物合成的一个主要假说,包括内源性大麻素花生四烯酸乙醇胺(AEA),认为它依赖于N-酰基磷脂酰乙醇胺(NAPE)被一种NAPE特异性磷脂酶D(NAPE-PLD)水解。因此,删除NAPE-PLD应该会降低NAE水平。先前对两种不同的NAPE-PLD基因敲除(KO)品系的分析,就NAPE-PLD对AEA生物合成的重要性产生了相互矛盾的数据。在这里,我们用一种脂质组未被表征的NAPE-PLD KO小鼠品系来检验这一假说。使用高效液相色谱/串联质谱法(HPLC/MS/MS),在KO小鼠和野生型(WT)小鼠的8个脑区中分析了70多种脂质,包括AEA代谢物N-花生四烯酰甘氨酸(NAGly)、内源性大麻素2-花生四烯酰甘油(2-AG)和前列腺素(PGE(2)和PGF(2α)),以及60多种脂胺。对这第三个NAPE-PLD KO品系的脂质组学分析表明,有广泛的脂质受到脂质种类和脑区的不同影响。重要的是,所测量的所有6种NAE都显著降低,尽管影响程度因脂肪酸饱和度长度和脑区而异。2-AG水平仅在脑干中受到影响,在KO小鼠中脑干中的水平显著升高。相应地,花生四烯酸水平仅在脑干中显著降低。NAGly水平在4个脑区显著升高,PGE(2)水平在KO小鼠的8个脑区中的6个脑区升高。这些数据表明,删除NAPE-PLD对脂质组的影响比以前认识到的要广泛得多。因此,抑制NAPE-PLD活性的行为特征可能是由于对脂质的多种影响,而不仅仅是由于AEA生物合成减少。