Metabolic basis of neuronal vulnerability to ischemia; an in vivo untargeted metabolomics approach

Abstract

Understanding the root causes of neuronal vulnerability to ischemia is paramount to the development of new therapies for stroke. Transient global cerebral ischemia (tGCI) leads to selective neuronal cell death in the CA1 sub-region of the hippocampus, while the neighboring CA3 sub-region is left largely intact. By studying factors pertaining to such selective vulnerability, we can develop therapies to enhance outcome after stroke. Using untargeted liquid chromatography-mass spectrometry, we analyzed temporal metabolomic changes in CA1 and CA3 hippocampal areas following tGCI in rats till the setting of neuronal apoptosis. 64 compounds in CA1 and 74 in CA3 were found to be enriched and statistically significant following tGCI. Pathway analysis showed that pyrimidine and purine metabolism pathways amongst several others to be enriched after tGCI in CA1 and CA3. Metabolomics analysis was able to capture very early changes following ischemia. We detected 6 metabolites to be upregulated and 6 to be downregulated 1 hour after tGCI in CA1 versus CA3. Several metabolites related to apoptosis and inflammation were differentially expressed in both regions after tGCI. We offer a new insight into the process of neuronal apoptosis, guided by metabolomic profiling that was not performed to such an extent previously.Metabolomics is the study of metabolite composition of cells, tissues or biological fluids. Recent technological advances in this field has allowed the discovery of new biomarkers of diseases such as coronary artery disease, septic shock and brain tumors as well as the discovery of new drugs 1-5 . Metabolomic analysis has also deepened our understanding of several disease models, leading to the discovery of new pathways or targets for drug therapies that could later be applied to the treatment of various diseases [6][7][8][9][10][11] . Indeed, metabolomics are closer to the phenotype of a given disease compared with transcriptomic or proteomic analysis, both of which are prone to downstream modifications and changes in activities 1,12 .Several techniques, tools and software platforms exist to study metabolomics, all of which complement each other 13 . The application of these tools has greatly enhanced our understanding of the pathophysiology of diseases in almost every field of research 14 . In the field of neuroscience, metabolomic analysis is used to study stroke 15 , brain tumors 16 , traumatic brain injury (TBI) 17,18 , neurodegenerative diseases 19 , hypoxic-ischemic encephalopathy 20 and depression 21 to name a few 22 . The application of metabolomic tools to study brain diseases have greatly enhanced our understanding of different pathologies, for example; we demonstrated the upregulation of the ceramide "Cer(d18:0/18:0)" and phosphocreatine following transient ischemia-reperfusion in mice using a mass spectrometric imaging approach 15 . Several studies have highlighted an array of small molecules, amino acids and lipids that were linked to stroke severity, progression or post-stroke cognitive deficits [23][...

Metabonomics Study on Naotaifang Extract Alleviating Neuronal Apoptosis after Cerebral Ischemia-Reperfusion Injury

“…The metabolic pathway involved in the differential metabolites, adenosine and inosine, is purine metabolism, which has been proved to play a significant role in the CIRI [ 17 ]. Adenosine is an important neuromodulator, which not only regulates Alzheimer's disease, Parkinson's disease, epilepsy, inflammation, cancer, and other diseases but also alleviates the injuries caused by cerebral ischemia and reperfusion [ 18 ].…”

Stop the rot. Enzyme inactivation at brain harvest prevents artifacts

“…Failure to prevent post-mortem metabolism is a common problem, and there are many examples of MS-or proton magnetic resonance spectroscopy ( 1 H-MRS)-based studies that did not stop brain metabolism at harvest (e.g., using decapitation, dissection, then freezing or perfusion to remove blood followed by tissue processing), including but not limited to the following reports: (Bergin et al, 2018;Blatherwick et al, 2013;Chabrun et al, 2020;Choi et al, 2018Choi et al, , 2019Citti et al, 2018;Dewan et al, 2020;González-Domínguez et al, 2014;Gonzalez-Riano et al, 2017;Hu et al, 2012;Huang et al, 2019;Hunsberger et al, 2020;Kleinridders et al, 2018;Kopp et al, 2010;Liao et al, 2019;Pan et al, 2017;Patti et al, 2012;Petroff et al, 1989;Randall et al, 2020;Rashad et al, 2020;Rzagalinski et al, 2019;Salek et al, 2010;Sugiyama et al, 2019;Vetel et al, 2019;Yi et al, 2020;Zheng et al, 2018Zheng et al, , 2020.…”

“…Pathway analysis with MetaboAnalyst of brain tissue after cardiac arrest (Choi et al, 2019) included the Val, Leu, Ile and Phe, Tyr, Trp biosynthesis pathways and D-Gln and D-Glu metabolism. The Phe-Trp and Val, Leu, Ile biosynthesis pathways were also included in the analysis after ischemia (Rashad et al, 2020).…”

Neuroprotective Effects of Purpurin Against Ischemic Damage via MAPKs, Bax, and Oxidative Stress Cascades in the Gerbil Hippocampus

“…Ischemic stroke is a life-threatening disease that affects approximately 15 million people worldwide annually [ 1 ]. Interruption of the blood flow into the brain causes a reduction in the supply of oxygen and glucose into the brain, resulting in damage to affected areas, including the hippocampus [ 2 , 3 ]. Reperfusion of interrupted vessels into the brain enormously increases the blood supply to the brain, but glucose metabolism is impaired via the pyruvate dehydrogenase pathway in neurons and pyruvate carboxylase pathway in astrocytes [ 4 ].…”