title: Molecular mechanisms of 6-hydroxydopamine-induced cytotoxicity in PC12 cells: involvement of hydrogen peroxide-dependent and -independent action.
abstract: The neurotoxin 6-hydroxydopamine (6-OHDA) has been widely used to generate an experimental model of Parkinson's disease. It has been reported that reactive oxygen species (ROS), such as the superoxide anion and hydrogen peroxide (H2O2), generated from 6-OHDA are involved in its cytotoxicity; however, the contribution and role of ROS in 6-OHDA-induced cell death have not been fully elucidated. In the present study using PC12 cells, we observed the generation of 50 microM H2O2 from a lethal concentration of 100 microM 6-OHDA within a few minutes, and compared the sole effect of H2O2 with 6-OHDA. Catalase, an H2O2-removing enzyme, completely abolished the cytotoxic effect of H2O2, while a significant but partial protective effect was observed against 6-OHDA. 6-OHDA induced peroxiredoxin oxidation, cytochrome c release, and caspase-3 activation. Catalase exhibited a strong inhibitory effect against the peroxiredoxin oxidation, and cytochrome c release induced by 6-OHDA; however, caspase-3 activation was not effectively inhibited by catalase. On the other hand, 6-OHDA-induced caspase-3 activation was inhibited in the presence of caspase-8, caspase-9, and calpain inhibitors. These results suggest that the H2O2 generated from 6-OHDA plays a pivotal role in 6-OHDA-induced peroxiredoxin oxidation, and cytochrome c release, while H2O2- and cytochrome c-independent caspase activation pathways are involved in 6-OHDA-induced neurotoxicity. These findings may contribute to explain the importance of generated H2O2 and secondary products as a second messenger of 6-OHDA-induced cell death signal linked to Parkinson's disease.
authors.affiliation: Human Stress Signal Research Center, National Institute of Advanced Industrial Science and Technology, Kansai Center, 1-8-31 Midorigaoka, Ikeda, Osaka 563-8577, Japan. yoshiro-saito@aist.go.jp
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Saito
authors.forename: Keiko
authors.initials: K
authors.lastname: Nishio
authors.forename: Yoko
authors.initials: Y
authors.lastname: Ogawa
authors.forename: Tomoya
authors.initials: T
authors.lastname: Kinumi
authors.forename: Yasukazu
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Yoshinori
authors.initials: Y
authors.lastname: Masuo
authors.forename: Etsuo
authors.initials: E
authors.lastname: Niki
mesh_terms: D000818:Animals; D000975:Antioxidants / Q000494:pharmacology; D016227:Benzoquinones / Q000378:metabolism; D002374:Catalase / Q000502:physiology; D016923:Cell Death / Q000187:drug effects; D002470:Cell Survival / Q000187:drug effects; D045304:Cytochromes c / Q000378:metabolism; D003603:Cytotoxins / Q000009:adverse effects; D006861:Hydrogen Peroxide / Q000494:pharmacology*; D008954:Models, Biological; D010084:Oxidation-Reduction; D016627:Oxidopamine / Q000494:pharmacology*; D016716:PC12 Cells; D010544:Peroxidases / Q000378:metabolism; D054464:Peroxiredoxins; D051381:Rats; D015398:Signal Transduction / Q000187:drug effects
chemical_list: D000975:Antioxidants; D016227:Benzoquinones; D003603:Cytotoxins; C004532:quinone; D016627:Oxidopamine; D045304:Cytochromes c; D006861:Hydrogen Peroxide; D010544:Peroxidases; D054464:Peroxiredoxins; D002374:Catalase