Characterizing Region-Specific Glucose Metabolic Profile of the Rodent Brain Using Seahorse XFe96 Analyzer
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Purpose: The brain is highly complex with diverse structural characteristics in accordance with specific functions. Accordingly, differences in regional function, cellular compositions, and active metabolic pathways may link to differences in glucose metabolism at different brain regions. A recent study using imaging mass spectrometry demonstrated that some of the glucose metabolism enzymes and ATP level vary dramatically cross the brain. Disruption of glucose metabolism forms the pathophysiological basis for many brain disorders. Therefore, the brain spatial metabolic signatures are of high relevance in our understanding of the normal brain physiology and neuropathology of neurological diseases. Method: We optimized an acute biopsy punching method and characterized region-specific glucose metabolism of rat and mouse brain by a Seahorse XFe96 analyzer. Results: In the current study, we demonstrated that 0.5 mm diameter tissue punches from 180-µm thick brain sections allow metabolic measurements of anatomically defined brain structures using Seahorse XFe96 analyzer. We found that the cerebellum displays a more quiescent phenotype of glucose metabolism than cerebral cortex, basal ganglia, and hippocampus. In addition, the cerebellum has higher AMPK activation than other brain regions evidenced by the expression of pAMPK, upstream pLKB1, and downstream pACC. Furthermore, rodent brain has relatively low mitochondrial oxidative phosphorylation efficiency with up to 30% of respiration linked to proton leak. Conclusions: The present study determined the region-specific glucose metabolic profile of rodent brain using acute biopsy punches and Seahorse XFe96 analyzer. The metabolic flux analysis indicated that the cerebellum has a more quiescent phenotype of glucose metabolism as compared with the cerebrum. In addition, glucose metabolism might be less efficient in the brain than we expected, with relatively large component of proton leak-linked respiration.