Reperfusion promotes mitochondrial dysfunction following focal cerebral ischemia in rats

Mitochondrial dysfunction has been implicated in the cell death observed after cerebral ischemia, and several mechanisms for this dysfunction have been proposed. Reperfusion after transient cerebral ischemia may cause continued and even more severe damage to the brain. Many lines of evidence have sh...

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Bibliographic Details
Published in:	PloS one Vol. 7; no. 9; p. e46498
Main Authors:	Li, Jun, Ma, Xuesong, Yu, Wei, Lou, Zhangqun, Mu, Dunlan, Wang, Ying, Shen, Baozhong, Qi, Sihua
Format:	Journal Article
Language:	English
Published:	United States Public Library of Science 28-09-2012 Public Library of Science (PLoS)
Subjects:	Anesthesiology Animals Apoptosis Biology Brain damage Brain injury Calcium Calcium (mitochondrial) Calcium - pharmacology Calcium - physiology Calcium content Care and treatment Cell death Centrifugation Cerebral blood flow Cerebral ischemia Complications and side effects Cyclophilins - metabolism Cytochrome Density gradients Flow cytometry Fluorescence Fluorescent indicators Infarction, Middle Cerebral Artery - metabolism Infarction, Middle Cerebral Artery - pathology Ischemia Laboratory animals Light Male Medicine Membrane potential Membrane Potential, Mitochondrial Metabolism Microscopy, Electron, Transmission Mitochondria Mitochondria - metabolism Mitochondria - pathology Mitochondria - physiology Mitochondrial diseases Mitochondrial DNA Mitochondrial Swelling Neurons Oxidation Oxidative stress Peptidyl-Prolyl Isomerase F Permeability Rats Rats, Wistar Reactive Oxygen Species - metabolism Reperfusion Reperfusion (Physiology) Reperfusion Injury - metabolism Reperfusion Injury - pathology Risk factors Rodents Scattering, Radiation Species Spectrophotometry Stains Stroke Swelling Traumatic brain injury Western blotting China Beijing China United States > US
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Summary:	Mitochondrial dysfunction has been implicated in the cell death observed after cerebral ischemia, and several mechanisms for this dysfunction have been proposed. Reperfusion after transient cerebral ischemia may cause continued and even more severe damage to the brain. Many lines of evidence have shown that mitochondria suffer severe damage in response to ischemic injury. The purpose of this study was to observe the features of mitochondrial dysfunction in isolated mitochondria during the reperfusion period following focal cerebral ischemia. Male Wistar rats were subjected to focal cerebral ischemia. Mitochondria were isolated using Percoll density gradient centrifugation. The isolated mitochondria were fixed for electron microscopic examination; calcium-induced mitochondrial swelling was quantified using spectrophotometry. Cyclophilin D was detected by Western blotting. Fluorescent probes were used to selectively stain mitochondria to measure their membrane potential and to measure reactive oxidative species production using flow cytometric analysis. Signs of damage were observed in the mitochondrial morphology after exposure to reperfusion. The mitochondrial swelling induced by Ca(2+) increased gradually with the increasing calcium concentration, and this tendency was exacerbated as the reperfusion time was extended. Cyclophilin D protein expression peaked after 24 hours of reperfusion. The mitochondrial membrane potential was decreased significantly during the reperfusion period, with the greatest decrease observed after 24 hours of reperfusion. The surge in mitochondrial reactive oxidative species occurred after 2 hours of reperfusion and was maintained at a high level during the reperfusion period. Reperfusion following focal cerebral ischemia induced significant mitochondrial morphological damage and Ca(2+)-induced mitochondrial swelling. The mechanism of this swelling may be mediated by the upregulation of the Cyclophilin D protein, the destruction of the mitochondrial membrane potential and the generation of excessive reactive oxidative species.
Bibliography:	Conceived and designed the experiments: SHQ. Performed the experiments: JL XSM WY YW DM. Analyzed the data: ZQL. Contributed reagents/materials/analysis tools: BZS. Wrote the paper: SHQ JL. Competing Interests: The authors have declared that no competing interests exist.
ISSN:	1932-6203 1932-6203
DOI:	10.1371/journal.pone.0046498