2000 Fiscal Year Final Research Report Summary
Molecular mechanisms of photoreceptor apoptosis and its control in animal model for retinitis pigmentosa
| Project/Area Number |
11671763
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Ophthalmology
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| Research Institution | Kansai Medical University |
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Principal Investigator |
SENZAKI Hideto Kansai Med. Univ., Faculty of Medicine, Assistant Professor, 医学部, 講師 (10206659)
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| Co-Investigator(Kenkyū-buntansha) |
SAYAMA Kazutoshi Shizuoka Univ., Faculty of Agriculture, Associate Professor, 農学部, 助教授 (30260582)
MIKI Hirohiko Kansai Med. Univ., Faculty of Medicine, Associate Professor, 医学部, 助教授 (30077771)
TSUBURA Airo Kansai Med. Univ., Faculty of Medicine, Professor, 医学部, 教授 (90098137)
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| Project Period (FY) |
1999 – 2000
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| Keywords | retinitis pigmentosa / photoreceptor cell / apoptosis / retinal degeneration / Bcl-2 / Bax / Caspase / Caspase-3 inhibitor |
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| Research Abstract |
A single intraperitoneal injection of 75 mg/kg N-methyl-N-nitrosourea (MNU) was given to 50-day-old female Sprague-Dawley rats and examined sequentially 12 and 24 hours, and 3 and 7 days after MNU treatment. Photoreceptor cell death was evoked in all treated rats. After MNU treatment, 7-methyldeoxyguanosine DNA adduct was detected selectively in photoreceptor cell nuclei at 12 hours, followed by photoreceptor cell apoptosis as confirmed by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-digoxigenin nick-end labeling (TUNEL) signals which peaked at 24 hours and continued until day 7 when several layers of photoreceptor cell nuclei were left. In apoptosis cascade, down-regulation of Bcl-2 was seen at 12 hours and up-regulation of Bax was seen at 24 hours, and caspase family (caspase 3/CPP32, caspase 6/Mch2, and caspase 8/FLICE protease) activities peaked 72 hours after MNU treatment. Therefore MNU-induced photoreceptor cell death was attributed to DNA adduct formation restricted to photoreceptor cell nuclei leading to photoreceptor cell apoptosis by up-regulation of Bax protein, down-modulation of Bcl-2 protein, and activation of caspase 3, 6, and 8. To test the effect of caspase-3 inhibitor, 4000 ng Ac-DEVD-CHO, was injected intraviterally twice at 0 and 10 hour after 60 mg/kg MNU, Caspase-3 inhibitor was effective in the suppression of MNU-induced photoreceptor apoptosis 3days after MNU, and suppressed the retinal damage 7 days after MNU.Thus the use of caspase-3 inhibitor may be a therapeutic intervention in human retinitis pigmentosa.
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