High-Resolution Spatiotemporal Mapping of Cerebral Metabolism During Middle-Cerebral-Artery Occlusion/Reperfusion Progression: Preliminary Insights

TL;DR

This study uses advanced imaging and analysis to track metabolic changes in the brain during a stroke and its aftermath, revealing new insights into injury progression.

Contribution

The first high-resolution spatiotemporal metabolic maps of early ischemic stroke in a rodent model are presented.

Findings

Metabolic abnormality spreads from the striatum to the cortex during ischemia.

Delayed clearance of urea and tryptamine during reperfusion contributes to injury progression.

Early depletion of pyrimidine synthesis pathways indicates compromised cellular repair mechanisms.

Abstract

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 the system 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 the striatum to the 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.

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