Metabolic alterations induced by ischemia in primary cultures of astrocytes: merging 13C NMR spectroscopy and metabolic flux analysis.
Disruption of brain energy metabolism is the hallmark of cerebral ischemia, a major cause of death worldwide. Astrocytes play a key role in the regulation of brain metabolism and their vulnerability to ischemia has been described. Aiming to quantify the effects of an ischemic insult in astrocytic metabolism, primary cultures of astrocytes were subjected to 5 h of oxygen and glucose deprivation in a bioreactor. Flux distributions, before and after ischemia, were estimated by metabolic flux analysis using isotopic information and the consumption/secretion rates of relevant extracellular metabolites as constraints. During ischemia and early recovery, 30% of cell death was observed; several metabolic alterations were also identified reflecting a metabolic response by the surviving cells. In the early recovery ( approximately 10 h), astrocytes up-regulated glucose utilization by 30% and increased the pentose phosphate pathway and tricarboxylic acid cycle fluxes by three and twofold, respectively. Additionally, a two to fivefold enhancement in branched-chain amino acids catabolism suggested the importance of anaplerotic molecules to the fast recovery of the energetic state, which was corroborated by measured cellular ATP levels. Glycolytic metabolism was predominant in the late recovery. In summary, this work demonstrates that changes in fluxes of key metabolic pathways are implicated in the recovery from ischemia in astrocytes.
Amaral
Ana I
AI
Instituto de Tecnologia Química e Biológica - Universidade Nova de Lisboa, and Instituto de Biologia Experimental e Tecnológica, Oeiras, Portugal.
Teixeira
Ana P
AP
Martens
Sanja
S
Bernal
Vicente
V
Sousa
Marcos F Q
MF
Alves
Paula M
PM
D000255:Adenosine Triphosphate / Q000378:metabolism; D000596:Amino Acids / Q000378:metabolism; D000597:Amino Acids, Branched-Chain / Q000378:metabolism; D000818:Animals; D001253:Astrocytes / Q000378:metabolism*; D019149:Bioreactors; D002545:Brain Ischemia / Q000378:metabolism*; D016923:Cell Death / Q000502:physiology; D015687:Cell Hypoxia / Q000502:physiology; D002470:Cell Survival / Q000502:physiology; D002478:Cells, Cultured; D005947:Glucose / Q000172:deficiency; D005973:Glutamine / Q000378:metabolism; D006019:Glycolysis / Q000502:physiology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D019344:Lactic Acid / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D009419:Nerve Tissue Proteins / Q000096:biosynthesis; D010085:Oxidative Phosphorylation; D010427:Pentose Phosphate Pathway / Q000502:physiology; D051381:Rats; D017207:Rats, Sprague-Dawley
D000596:Amino Acids; D000597:Amino Acids, Branched-Chain; D009419:Nerve Tissue Proteins; D005973:Glutamine; D019344:Lactic Acid; D000255:Adenosine Triphosphate; D007770:L-Lactate Dehydrogenase; D005947:Glucose