帕金森病早期SNCA基因Ala53Thr碱基替换对小鼠模型嗅球组织中内源性代谢产物表达的影响

Study on changes of endogenous metabolites in olfactory bulb of early-stage Parkinson’s disease induced by SNCA gene Ala53Thr base substitution in mice

目的探讨SNCA基因在帕金森病早期病理生理学机制中的作用。方法选择SNCA基因Ala53Thr碱基替换小鼠和野生型小鼠各10只,采用超高效液相色谱-串联质谱(HPLC-MS/MS)法分离嗅球组织代谢产物,采用主成分分析、判别分析、聚类分析等筛选并验证代谢产物,代谢组学分析嗅球组织内源性代谢产物,并构建代谢通路图和网络图以明确相关代谢通路及差异内源性代谢产物之间的关系。结果最终确定29个变量为差异代谢产物,其中,内源性代谢产物磷脂酰胆碱、磷脂酰乙醇胺、维生素C、鞘磷脂、磷脂酰甘油和谷氨酸相对表达量在TG组有所上升(均P<0.05),且上述代谢产物的相对表达量与下调的差异代谢产物之间呈负相关;而磷脂、牛磺酸、缬氨酸、神经酰胺和γ-氨基丁酸(GABA)相对表达量在TG组有所下降(均P<0.05),且上述代谢产物的相对表达量之间呈正相关。相关代谢通路主要涉及牛磺酸和亚牛磺酸代谢通路,谷氨酰胺和谷氨酸代谢通路,维生素C代谢通路,磷脂酰甘油代谢通路,丙氨酸、天冬氨酸和谷氨酸代谢通路,包括牛磺酸、D-谷氨酸、维生素C、卵磷脂、溶血性磷脂酰胆碱[18:2(9Z,12Z)]和GABA共6种标志性代谢成分。结论本研究验证帕金森病早期即可出现嗅球组织病理变化,SNCA基因Ala53Thr碱基替换的直接作用导致磷脂类代谢改变,并引起神经功能紊乱。

Objective To explore the pathophysiologic mechanism of SNCA gene in the early-stage of Parkinson’s disease(PD).Methods Wild type(WT group,n=10)and SNCA Ala53 Thr base substitution mice(TG group,n=10)were selected for further experiments.Endogenous metabolites in olfactory bulb(OB)of transgenic and wild type mice were detected and analyzed by high performance liquid chromatography-tandem mass spectrometry(HPLC-MS/MS).Then the endogenous metabolites were identified through mzCloud and determined by molecular formula and molecular weight.The differential endogenous metabolites were obtained by principal component analysis(PCA),partial least squares discrimination analysis(PLS-DA),orthogonal partial least squares discriminant analysis(OPLS-DA)and cluster analysis.Finally,the pathway and interaction network between the differential endogenous metabolites and corresponding pathways were constructed.Results Finally 29 variations were identified as differential metabolites.Among them,the relative expressions of phosphatidylcholine(PC),phosphatidylethanolamine(PE),vitamin C,sphingomyelin(SM),phosphatidylglycerol(PG)and glutamic acid were elevated in TG group(P<0.05,for all)and the negative relationship was shown between elevated metabolite and decreased metabolite in relative expression,while the relative expressions of phosphalipids,taurine,ceramide valine andγ-aminobutyric acid(GABA)were decreased in TG group(P<0.05,for all)and the relationship of relative expression among them was positive.The related metabolic pathways were mainly associated with the taurine and hypotaurine metabolism,glutamine and glutamate metabolism,ascorbate and aldarate metabolism,glycerophospholipid metabolism and alanine,aspartate and glutamate metabolism,included taurine,D-glutamate,vitamine C,phospholipid,LysoPC[18:2(9 Z,12 Z)]and GABA all 6 significant metabolites.Conclusions The experiment verified pathological changes of OB in the early stage of PD.Meanwhile the differences in phosphatides could be a direct result of SNCA Ala53 Thr mutation.Furthermore,malfunction of neurons in OB is also observed and may be contributed to the abnormal phosphatides’metabolism.