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  • 1
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Mitochondria are important in the pathophysiology of several neurodegenerative diseases, and mitochondrial production of reactive oxygen species (ROS), membrane depolarization, permeability changes and release of apoptogenic proteins are involved in these processes. Following brain insults, cell death often occurs in discrete regions of the brain, such as the subregions of the hippocampus. To analyse mitochondrial structure and function in such subregions, only small amounts of mitochondria are available. We developed a protocol for flow cytometric analysis of very small samples of isolated brain mitochondria, and analysed mitochondrial swelling and formation of ROS in mitochondria from the CA1 and CA3 regions of the hippocampus. Calcium-induced mitochondrial swelling was measured, and fluorescent probes were used to selectively stain mitochondria (nonyl acridine orange), to measure membrane potential (tetramethylrhodamine-methyl-ester, 1,1′,3,3,3′,3′-hexamethylindodicarbocyanine-iodide) and to measure production of ROS (2′,7′-dichlorodihydrofluorescein-diacetate). We found that formation of ROS and mitochondrial permeability transition pore activation were higher in mitochondria from the CA1 than from the CA3 region, and propose that differences in mitochondrial properties partly underlie the selective vulnerability of the CA1 region to brain insults. We also conclude that flow cytometry is a useful tool to analyse the role of mitochondria in cell death processes.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 1471-4159
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: Abstract: Mitochondria from different regions of the brain wereprepared, and the activation of the mitochondrial permeability transition(MPT) by calcium was investigated by monitoring the associated mitochondrialswelling. In general, the properties of the MPT in brain mitochondria werefound to be qualitatively similar to those observed in liver and heartmitochondria. Thus, swelling was inhibited by adenine nucleotides (AdNs) andlow pH (〈7.0), whereas thiol reagents and alkalosis facilitated swelling.Cyclosporin A and its nonimmunosuppressive analogueN-methyl-Val-4-cyclosporin A (PKF 220-384) both inhibited swellingand prevented the translocation of cyclophilin D from the matrix to themembranes of cortical mitochondria. However, the calcium sensitivity of theMPT differed in mitochondria from three brain regions (hippocampus 〉 cortex〉 cerebellum) and is correlated with the susceptibility of these regions toischemic damage. Depleting mitochondria of AdNs by treatment withpyrophosphate ions sensitized the MPT to [Ca2+] and abolished regional differences, implying regional differences in mitochondrial AdN content. This was confirmed by measurements showing significant differences in AdN content among regions (cerebellum 〉 cortex 〉 hippocampus). Our data add to recent evidence that the MPT may be involved in neuronal death.
    Type of Medium: Electronic Resource
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  • 3
    ISSN: 1460-9568
    Source: Blackwell Publishing Journal Backfiles 1879-2005
    Topics: Medicine
    Notes: When mouse hippocampal neuronal cultures, 2–3 weeks in vitro, were transiently exposed to combined glucose and oxygen deprivation (100% argon, 5% CO2, in glucose-free medium) for 90 min, extensive neuronal degeneration had occurred after 24 h of reoxygenation. When these cultures were preincubated with cyclosporin A, a calcineurin inhibitor and a blocker of the mitochondrial permeability transition, neuronal death diminished by 30–50%. Similarly, the cyclosporin A analogue, N-Me-Val-4-cyclosporin A, a potent blocker of the mitochondrial permeability transition with no significant calcineurin blocking activity, decreased cell death by 70–80%. Both cyclosporin A and N-Me-Val-4-cyclosporin A markedly attenuated calcium-induced swelling of isolated mouse brain mitochondria by blocking the mitochondrial permeability transition. The potassium thiocyanate-stabilized binding of cyclophilin D to mouse brain mitochondrial membranes was completely prevented by cyclosporin A and N-Me-Val-4-cyclosporin A. Our results strongly suggest that the mitochondrial permeability transition is involved in oxygen/glucose deprivation-induced cell death in vitro. Cyclophilin D and other components of the mitochondrial permeability transition may be important targets for neuroprotective and anti-ischaemic drugs.
    Type of Medium: Electronic Resource
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