title: Adenosine production by brain cells.
abstract: The early release of adenosine following traumatic brain injury (TBI) suppresses seizures and brain inflammation; thus, it is important to elucidate the cellular sources of adenosine following injurious stimuli triggered by TBI so that therapeutics for enhancing the early adenosine-release response can be optimized. Using mass spectrometry with13C-labeled standards, we investigated in cultured rat neurons, astrocytes, and microglia the effects of oxygen-glucose deprivation (OGD; models energy failure), H2O2(produces oxidative stress), and glutamate (induces excitotoxicity) on intracellular and extracellular levels of 5'-AMP (adenosine precursor), adenosine, and inosine and hypoxanthine (adenosine metabolites). In neurons, OGD triggered increases in intracellular 5'-AMP (2.8-fold), adenosine (2.6-fold), inosine (2.2-fold), and hypoxanthine (5.3-fold) and extracellular 5'-AMP (2.2-fold), adenosine (2.4-fold), and hypoxanthine (2.5-fold). In neurons, H2O2did not affect intracellular or extracellular purines; yet, glutamate increased intracellular adenosine, inosine, and hypoxanthine (1.7-fold, 1.7-fold, and 1.6-fold, respectively) and extracellular adenosine, inosine, and hypoxanthine (2.9-fold, 2.1-fold, and 1.6-fold, respectively). In astrocytes, neither H2O2nor glutamate affected intracellular or extracellular purines, and OGD only slightly increased intracellular and extracellular hypoxanthine. Microglia were unresponsive to OGD and glutamate, but were remarkably responsive to H2O2, which increased intracellular 5'-AMP (1.6-fold), adenosine (1.6-fold), inosine (2.1-fold), and hypoxanthine (1.6-fold) and extracellular 5'-AMP (5.9-fold), adenosine (4.0-fold), inosine (4.3-fold), and hypoxanthine (1.9-fold).
  
  
  
  Under these particular experimental conditions, cultured neurons are the main contributors to adenosine production/release in response to OGD and glutamate, whereas cultured microglia are the main contributors upon oxidative stress. Developing therapeutics that recruit astrocytes to produce/release adenosine could have beneficial effects in TBI.
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Edwin K
authors.identifier: 0000-0002-8101-6009
authors.initials: EK
authors.lastname: Jackson
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Shawn E
authors.initials: SE
authors.lastname: Kotermanski
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Elizabeth V
authors.initials: EV
authors.lastname: Menshikova
authors.affiliation: Department of Pharmacology and Chemical Biology, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.|Department of Reproductive Endocrinology, University Hospital Zurich and Zurich Center for Integrative Human Physiology (ZIHP), University of Zurich, Zurich, Switzerland.
authors.forename: Raghvendra K
authors.initials: RK
authors.lastname: Dubey
authors.affiliation: Department of Critical Care Medicine and the Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Travis C
authors.initials: TC
authors.lastname: Jackson
authors.affiliation: Department of Critical Care Medicine and the Safar Center for Resuscitation Research, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA.
authors.forename: Patrick M
authors.initials: PM
authors.lastname: Kochanek
mesh_terms: D000241:Adenosine / Q000378:metabolism*; D000818:Animals; D002135:Calcium-Binding Proteins / Q000378:metabolism; D002478:Cells, Cultured; D002540:Cerebral Cortex / Q000166:cytology*; D004622:Embryo, Mammalian; D004734:Energy Metabolism / Q000187:drug effects; D018690:Excitatory Amino Acid Agonists / Q000494:pharmacology; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism; D005947:Glucose / Q000172:deficiency; D018698:Glutamic Acid / Q000494:pharmacology; D006861:Hydrogen Peroxide / Q000494:pharmacology; D000860:Hypoxia / Q000473:pathology; D007770:L-Lactate Dehydrogenase / Q000378:metabolism; D008840:Microfilament Proteins / Q000378:metabolism; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism*; D009474:Neurons / Q000187:drug effects / Q000378:metabolism*; D010751:Phosphopyruvate Hydratase / Q000378:metabolism; D011247:Pregnancy; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: C100745:Aif1 protein, rat; D002135:Calcium-Binding Proteins; D018690:Excitatory Amino Acid Agonists; D005904:Glial Fibrillary Acidic Protein; D008840:Microfilament Proteins; D018698:Glutamic Acid; D006861:Hydrogen Peroxide; D007770:L-Lactate Dehydrogenase; D010751:Phosphopyruvate Hydratase; D005947:Glucose; D000241:Adenosine
keywords: 5′-AMP; adenosine; astrocytes; hypoxanthine; inosine; microglia; neurons