| Co-Investigator(Kenkyū-buntansha) |
TSUJIMOTO Aiko Yamanashi Med. College, Faculty of Medicine, Instructor, 医学部, 医員
NAKAGOMI Yoshiko Yamanashi Med. College, Faculty of Medicine, Instructor, 医学部, 助手 (20198055)
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| Research Abstract |
1. Thyrotoxic oxidative muscular injury model: Vitamin E, which acts as a chain-breaking antioxidant in biomembranes, prevented the acceleration of lipid peroxidation induced by thyroxine independently of the changes in mitochondrial oxidative metabolism and the antioxidant enzymes. Beta 1-blockade suppressed the lipid peroxidation in the cardiac muscle, while beta 2-blockade suppressed that in the skeletal muscle, mainly via normalization of mitochondrial oxidative metabolism. These results collectively suggest that superoxide generated in mitochondria mediates the oxidative injury.
2. Prenatal development of antioxidant enzymes: The antioxidant enzymes in the fetal rat lung and kidneys increased dramatically in late gestational period. The immunohistochemical localization of both copper-zinc and manganese superoxide dismutases, CuZnSOD and MnSOD, revealed the relative abundance of these enzymes in both respiratory epithelium and renal tubules, suggesting a rapid growth of these tissue
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s in that period. Dexamethasone, administered in the dam, facilitated the prenatal development of antioxidant enzymes in the pups. This is consistent with the clinical finding that dexamethasone reduces pulmonary morbidity of premature neonates by inducing maturation of the lung.
3. Effect of endogenous sex hormones on antioxidant enzymes: Postnatal development of antioxidant enzymes was evaluated in female and castrated and non-castrated male rats. The antioxidant enzymes in the adults tended to be higher than those in the weanling rats. There was no sex-related difference in the levels of CuZnSOD and MnSOD. On the other hand, estrogens increased glutathione peroxidase and decreased catalase in the liver. Conversely, androgens increased the catalase and decreased the glutathione peroxidase. The latter is known to be a more potent scavenger of physiologic intracellular concentration of H_2O_2 than catalase. Thus, this result supports the contention that females have a higher antioxidant capacity and a more chance to enjoy longevity than males. Less
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