MCAO大鼠脑缺血再灌注损伤机制的核磁共振代谢组学研究

NMR-based metabolomic investigation of regional brain tissue dysfunctions of MCAO rats induced by ischemia

运用MCAO方法建立了大鼠局灶性脑缺血模型,随后通过开展针对MCAO大鼠的NMR代谢组学研究来阐明缺血再灌注早期缺血半脑脑组织以及对侧半脑脑组织的代谢物组改变和相关联的脑损伤机制。结果表明:脑缺血再灌注后3 h缺血半脑脑组织的不同区域均在一定程度上产生了能量不足(单磷酸腺苷水平下降;尿嘧啶含量升高)、无氧酵解上调(乳酸含量显著升高)、氧化应激(丙二酸、琥珀酸含量上升)、磷脂代谢异常(胆碱水平显著升高;磷酰胆碱和甘油磷酰胆碱含量下降)、神经递质紊乱(谷氨酸含量下降;γ-氨基丁酸、甘氨酸、丙氨酸含量升高)和神经细胞损伤(N-乙酰天冬氨酸含量下降)等应激性变化,而对侧非缺血端半脑脑组织的代谢模式改变总体上与左脑相类似,但发生显著性变化的代谢物的数量明显比左脑少,能量匮乏的程度也比左脑小,研究结果提示在局灶性脑卒中病人治疗过程中,非缺血损伤端同样应该受到关注。

In this paper,an NMR-based metabolomic study was applied to unravel the pathological mechanisms of focal cerebral ischemia at the metabolic level by investigating the metabolic profile changes of regional brain tissues of male rats upon MCAO operation. In our study,to induce ischemic defects,the operation of middle cerebral artery occlusion was applied to rats in the model group. Meanwhile,the sham-operation was subjected to the rats in sham group by following the same surgical procedure as that applied to the model group rats without occlusion. Three hours after the operation, the metabolites from regional brain tissues including cortex, hippocampus and striatum from the ischemic left hemisphere and the non-ischemic right hemisphere of experimental rats were extracted and subjected to NMR. Multivariate data analysis of PCA and OPLS-DA methods were then applied to analyze the NMR data and thus unravel the possible correlations between the metabolic profile changes and the variations in biological pathways of MCAO rats. The obtained metabolomic data demonstrated that the neural cell damages and the systematic metabolic disorders including energy deficiency（ the decrease in AMP level and the increase in uridine concentration）,up-regulation of anaerobic glycolysis（ a significant up-regulation of the lactate level）,oxidative stress（ the up-regulation of either malonate level or succinate concentration）, dysfunction of choline metabolism（ the significant up-regulation of choline level and the decrease in both GPC level and phosphorylcholine concentration）, neurotransmitter imbalances（ the down-regulation of glutamate level and the upregulation of GABA, glycine and alanine concentration）, and neuronal cell damage（ a decrease in the NAA level）,were induced in the regional brain tissues of ischemic left hemispheres of MCAO rats. Moreover, the patterns of the metabolic variations in the non-ischemic hemispheres of MCAO rats were similar to those in the left ones, although the metabolic disorders in the non-ischemic right hemisphere were much less severe. Our results suggest that close attention should be paid to the non-ischemic cerebral regions in the treatment of patients with focal ischemic stroke.