title: Superoxide generation in different brain regions of rats during normoxia and hypoxia-reoxygenation.
abstract: The superoxide-dependent chemiluminescent intensity in different brain regions was examined in ex vivo tissue slices of rat brain during normoxia and hypoxia-reoxygenation with lucigenin. The chemiluminescent intensity increased during reoxygenation after hypoxic treatment. There was a higher level of chemiluminescent intensity in the hippocampus during normoxia, and a lower level in the white matter during normoxia and hypoxia-reoxygenation. A weak correlation was found between the chemiluminescent intensity and the glucose uptake rate during normoxia. Then we examined whether hypoxic strength correlates to superoxide generation. The chemiluminescent intensity increased in a hypoxic strength-dependent manner. The generation mechanism of superoxide was examined using carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial uncoupler, genipin, an inhibitor for uncoupling protein-2, alloprinol, a xanthine oxidase inhibitor, or apocynin, an NADPH oxidase inhibitor. The chemiluminescent signal was significantly inhibited by CCCP under normoxic condition and enhanced by genipin during normoxia and hypoxia-reoxygenation, but not by allopurinol or apocynin. These results suggest that superoxide generation is high in the hippocampus during normoxia and low in the white matter during normoxia and hypoxia-reoxygenation, superoxide generation in the hypoxia-reoxygenation brain correlates with the strength of hypoxia influenced by oxygen delivery, and mitochondrion is the major sites of intracellular superoxide generation.
authors.affiliation: Research Team for Molecular Mechanism of Aging, Redox Research, Tokyo Metropolitan Institute of Gerontology, Tokyo 173-0015, Japan. tsasaki@center.tmig.or.jp
authors.forename: Toru
authors.initials: T
authors.lastname: Sasaki
authors.forename: Masafumi
authors.initials: M
authors.lastname: Yamanaka
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Kagami
mesh_terms: D000818:Animals; D001921:Brain / Q000378:metabolism*; D002534:Hypoxia, Brain / Q000378:metabolism*; D008163:Luminescent Measurements / Q000379:methods; D008297:Male; D009924:Organ Culture Techniques; D051381:Rats; D017208:Rats, Wistar; D015427:Reperfusion Injury / Q000378:metabolism*; D013481:Superoxides / Q000032:analysis* / Q000378:metabolism
chemical_list: D013481:Superoxides