1991 Fiscal Year Final Research Report Summary
Mechanism of cytoprotection against neuronal damage
| Project/Area Number |
02670369
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| Research Category |
Grant-in-Aid for General Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Research Field |
Neurology
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| Research Institution | University of Occupational and Environmental Health |
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Principal Investigator |
OISHI Tomonari University of Occupational and Environmental Health, Faculty of Medicine (Lecturer), 医学部, 講師 (50038907)
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| Project Period (FY) |
1990 – 1991
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| Keywords | cytoprotection / active oxygen / MPTP / glutathione / glutathione peroxidase / MPP^+ / cysteamine / dimercaprol |
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| Research Abstract |
1. Determination of erythrocyte or brain glutathione peroxidase activity.
The washed erythrocytes are disrupted by freezing and thawing. The brains are homogenized in 5 volume of O. lM potassium phosphate buffer, pH7.0, by sonication. Lysate (50mul of erythrocyte or 30mul of brain sample) is added to 50 (or 10) mul of 0.1M phosphate buffer (pH7.0), 10 (or 5) mul of lOmM NaN_3, and 50 (or 10) mul of 4mM GSH. After equilibration of these mixture at 37ﾟC for 10 minutes, the reaction is initiated by adding 50 (or 10) mul of 5mM H_2O_2. After the incubation time, 7.5 (or 5) minutes, the reaction is stopped by injecting 200 (or 100) mul of 1.2M HC10_4. GSH contents of the assay mixture are measured by high-performance liquid chromatography with electrochemical detection.
G-Px activity is calculated as follows :
G-Px(Uk)=(log<@D7[GSH]<@D2O@>D2(/)[GSH]<@D2T@>D2@>D7 - log<@D7[GSH]<@D2O@>D2(/)[GSH]<@D2S@>D2@>D7) X <@D7Vi(/)Vs@>D7 X <@D7l(/)t@>D7
2. Determination of erythrocyte GSH GSSG contents and
… More
glutathione peroxidase activity.
In neurodegenerative disorders such as parkinsonism and spinocerebellar degeneration, erythrocyte GSH GSSG contents and G-Px activity are now being measured.
3. Also in neurodegenerative disorders, amino acid contents in serum and CSF, and mine metabolites (MHPG, HVA and 5-HIAA) in CSF are now being measured.
4. The NADH-supported formation of superoxide radicals was induced by MPP^+, a metabolite of a parkinsonism-inducing drug MPTP, in bovine heart submitochondrial particles. The NADH-supported lipid peroxidation by the particles in the presence of ADP-FE^<3+> chelate was also enhanced by MPP^+. The formation was inhibited by succinate and the reduction of endogeneous ubiquinone seemed to be related the inhibition.
5. Pretreatments of both cysteamine (200mg/kg, s. c.) and dimercaprol (20mg/kg, i. m.)reduced the MPTP-induced decreases in striatal dopamine, DOPAC and HVA, and also prevented the MPTP-induced decreases in GSH levels and increases in GSSG/GSH ratios. These results suggest that sulfhydryl drugs such as cysteamine and dimercaprol may reduce neurotoxicity of MPTP provably via changes in redox cycle of glutathione in the brain. Less
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