title: Single-cell imaging of bioenergetic responses to neuronal excitotoxicity and oxygen and glucose deprivation.
abstract: Excitotoxicity is a condition occurring during cerebral ischemia, seizures, and chronic neurodegeneration. It is characterized by overactivation of glutamate receptors, leading to excessive Ca(2+)/Na(+) influx into neurons, energetic stress, and subsequent neuronal injury. We and others have previously investigated neuronal populations to study how bioenergetic parameters determine neuronal injury; however, such experiments are often confounded by population-based heterogeneity and the contribution of effects of non-neuronal cells. Hence, we here characterized bioenergetics during transient excitotoxicity in rat and mouse primary neurons at the single-cell level using fluorescent sensors for intracellular glucose, ATP, and activation of the energy sensor AMP-activated protein kinase (AMPK). We identified ATP depletion and recovery to energetic homeostasis, along with AMPK activation, as surprisingly rapid and plastic responses in two excitotoxic injury paradigms. We observed rapid recovery of neuronal ATP levels also in the absence of extracellular glucose, or when glycolytic ATP production was inhibited, but found mitochondria to be critical for fast and complete energetic recovery. Using an injury model of oxygen and glucose deprivation, we identified a similarly rapid bioenergetics response, yet with incomplete ATP recovery and decreased AMPK activity. Interestingly, excitotoxicity also induced an accumulation of intracellular glucose, providing an additional source of energy during and after excitotoxicity-induced energy depletion. We identified this to originate from extracellular, AMPK-dependent glucose uptake and from intracellular glucose mobilization. Surprisingly, cells recovering their elevated glucose levels faster to baseline survived longer, indicating that the plasticity of neurons to adapt to bioenergetic challenges is a key indicator of neuronal viability.
authors: Department of Physiology and Medical Physics, Centre of Systems Medicine, and.
authors: Niamh M C
authors: http://orcid.org/0000-0002-6005-1307
authors: NM
authors: Connolly
authors: Department of Physiology and Medical Physics, Centre of Systems Medicine, and Centre for the Study of Neurological Disorders, Royal College of Surgeons in Ireland, Dublin 2, Ireland, and.
authors: Heiko
authors: H
authors: Düssmann
authors: Department of Physiology and Medical Physics, Centre for the Study of Neurological Disorders, Royal College of Surgeons in Ireland, Dublin 2, Ireland, and.
authors: Ujval
authors: U
authors: Anilkumar
authors: Department of Physiology and Medical Physics, Centre of Systems Medicine, and Department of Cardiovascular Sciences, KU Leuven, 3000 Leuven, Belgium prehn@rcsi.ie heinhuber@rcsi.ie.
authors: Heinrich J
authors: http://orcid.org/0000-0003-4454-2971
authors: HJ
authors: Huber
authors: Department of Physiology and Medical Physics, Centre of Systems Medicine, and Centre for the Study of Neurological Disorders, Royal College of Surgeons in Ireland, Dublin 2, Ireland, and prehn@rcsi.ie heinhuber@rcsi.ie.
authors: Jochen H M
authors: JH
authors: Prehn
mesh_terms: D000818:Animals; D000831:Animals, Newborn; D002118:Calcium / Q000378:metabolism; D002478:Cells, Cultured; D002531:Cerebellum / Q000166:cytology; D002540:Cerebral Cortex / Q000166:cytology; D003847:Deoxyglucose / Q000493:pharmacokinetics; D004734:Energy Metabolism / Q000502:physiology*; D005947:Glucose / Q000172:deficiency* / Q000378:metabolism; D018698:Glutamic Acid / Q000494:pharmacology; D005998:Glycine / Q000633:toxicity; D000860:Hypoxia; D008164:Luminescent Proteins / Q000235:genetics / Q000378:metabolism; D053078:Membrane Potential, Mitochondrial / Q000187:drug effects / Q000502:physiology; D051379:Mice; D009474:Neurons / Q000187:drug effects / Q000502:physiology*; D009498:Neurotoxins / Q000494:pharmacology; D061848:Optical Imaging; D051381:Rats; D059010:Single-Cell Analysis
chemical_list: D008164:Luminescent Proteins; D009498:Neurotoxins; D018698:Glutamic Acid; D003847:Deoxyglucose; D005947:Glucose; D002118:Calcium; D005998:Glycine
keywords: bioenergetics; excitotoxicity; single-cell imaging