High-resolution spatiotemporal mapping of cerebral metabolism during middle-cerebral-artery occlusion/reperfusion progression

Ischemia-reperfusion is a rapidly evolving cascade that involves a variety of metabolic shifts whose precise timing and sequential order are still poorly understood. Clarifying these dynamics is critical for understanding the core injury trajectory of stroke and for refining time-delimited therapeutic interventions. More broadly, continuous, in-situ monitoring of the middle-cerebral-artery occlusion process at systems level has not yet been achieved. Here, we report the first single-subject, High-resolution spatiotemporal resolution metabolic maps of the ultra-early phase of ischemic stroke in a rodent model. Matrix-Assisted Laser Desorption/Ionization Mass Spectrometry (MALDI-MS) imaging mapped a metabolic abnormality area in the ischemic hemisphere that propagates from striatum to cortex. Microdialysis probes were then stereotaxically implanted within this metabolic abnormality area, capturing 10,429 metabolites that resolved into 16 temporally distinct trajectories aligned with probe insertion, ischemic injury, and reperfusion injury. Analysis of specific metabolic pathways mainly revealed that the delayed clearance of metabolic waste (urea and tryptamine) during early reperfusion, the transient attenuation of the citrate-to-oxaloacetate buffering gradient within the TCA cycle, and the accumulation of extracellular branched-chain amino acids all play crucial roles in shaping the injury trajectory. Simultaneously, the depletion of cellular repair mechanisms (pyrimidine synthesis) in the early phase of reperfusion also warrants our attention. These findings provide novel insights into the molecular basis and mechanisms of Ischemia-reperfusion and offer a comprehensive resource for further investigation.

缺血再灌注（Ischemia-reperfusion）是一类快速进展的级联反应，涉及多种代谢转变，但其精确时序与先后顺序仍未被充分阐明。阐明这些动态变化，对于理解脑卒中的核心损伤进程以及优化时限性治疗干预手段至关重要。更广泛而言，目前尚未实现在系统层面对大脑中动脉闭塞过程进行连续的原位监测。本研究首次报道了啮齿类动物模型中缺血性脑卒中超早期阶段的单个体高时空分辨率代谢图谱。我们采用基质辅助激光解吸电离质谱（MALDI-MS）成像技术，在缺血侧大脑半球定位到一处从纹状体向大脑皮层扩散的代谢异常区域。随后，通过立体定位将微透析探针植入该代谢异常区域，共捕获10429种代谢物，这些代谢物可划分为16条时间特异性的动态轨迹，与探针植入、缺血性损伤及再灌注损伤的进程相契合。对特定代谢通路的分析主要揭示了以下关键发现：再灌注早期代谢废物（尿素与色胺）的清除延迟、三羧酸循环（TCA cycle）中柠檬酸至草酰乙酸的缓冲梯度出现短暂减弱，以及细胞外支链氨基酸的蓄积，均对损伤进程的塑造起到关键作用。与此同时，再灌注早期细胞修复机制（嘧啶合成）的耗竭也值得关注。本研究的发现为缺血再灌注的分子基础与损伤机制提供了全新见解，并为后续研究提供了全面的研究资源。