Astrocytic mitochondrial membrane hyperpolarization following extended oxygen and glucose deprivation

PLoS One. 2014 Feb 28;9(2):e90697. doi: 10.1371/journal.pone.0090697. eCollection 2014.

Abstract

Astrocytes can tolerate longer periods of oxygen and glucose deprivation (OGD) as compared to neurons. The reasons for this reduced vulnerability are not well understood. Particularly, changes in mitochondrial membrane potential (Δψ(m)) in astrocytes, an indicator of the cellular redox state, have not been investigated during reperfusion after extended OGD exposure. Here, we subjected primary mouse astrocytes to glucose deprivation (GD), OGD and combinations of both conditions varying in duration and sequence. Changes in Δψ(m), visualized by change in the fluorescence of JC-1, were investigated within one hour after reconstitution of oxygen and glucose supply, intended to model in vivo reperfusion. In all experiments, astrocytes showed resilience to extended periods of OGD, which had little effect on Δψ(m) during reperfusion, whereas GD caused a robust Δψ(m) negativation. In case no Δψ(m) negativation was observed after OGD, subsequent chemical oxygen deprivation (OD) induced by sodium azide caused depolarization, which, however, was significantly delayed as compared to normoxic group. When GD preceded OD for 12 h, Δψ(m) hyperpolarization was induced by both GD and subsequent OD, but significant interaction between these conditions was not detected. However, when GD was extended to 48 h preceding OGD, hyperpolarization enhanced during reperfusion. This implicates synergistic effects of both conditions in that sequence. These findings provide novel information regarding the role of the two main substrates of electron transport chain (glucose and oxygen) and their hyperpolarizing effect on Δψ(m) during substrate deprivation, thus shedding new light on mechanisms of astrocyte resilience to prolonged ischemic injury.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Astrocytes / cytology
  • Astrocytes / drug effects*
  • Astrocytes / metabolism
  • Benzimidazoles / metabolism
  • Carbocyanines / metabolism
  • Cell Hypoxia
  • Cells, Cultured
  • Enzyme Inhibitors / pharmacology
  • Fetus
  • Fluorescent Dyes / metabolism
  • Glucose / deficiency
  • Glucose / pharmacology*
  • Hydrogen Peroxide / pharmacology
  • Membrane Potential, Mitochondrial / drug effects*
  • Mice, Inbred BALB C
  • Microscopy, Fluorescence
  • Mitochondria / drug effects*
  • Mitochondria / metabolism
  • Mitochondria / physiology
  • Oxidants / pharmacology
  • Oxygen / metabolism
  • Oxygen / pharmacology*
  • Prosencephalon
  • Sodium Azide / pharmacology
  • Time Factors

Substances

  • Benzimidazoles
  • Carbocyanines
  • Enzyme Inhibitors
  • Fluorescent Dyes
  • Oxidants
  • 5,5',6,6'-tetrachloro-1,1',3,3'-tetraethylbenzimidazolocarbocyanine
  • Sodium Azide
  • Hydrogen Peroxide
  • Glucose
  • Oxygen

Grant support

This study was supported by intramural funds of the Fraunhofer Institute for Cell Therapy and Immunology (Department of Cell Therapy) and a DAAD (German Academic Exchange Service, Deutscher Akademischer Austauschdienst) short term research fellowship, as well as by the Serbian Ministry of Education and Science (III 41005). The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.