| Project/Area Number |
07671533
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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 |
Cerebral neurosurgery
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| Research Institution | NAGOYA CITY UNIVERSITY |
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Principal Investigator |
KANAI Hideki NAGOYA CITY UNIVERSITY MEDICAL SCHOOL, NEUROSURGERY, ASSISTANT PROFESSOR, 医学部, 講師 (90185893)
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| Co-Investigator(Kenkyū-buntansha) |
YAMADA Kazuo NAGOYA CITY UNIVERSITY MEDICAL SCHOOL, NEUROSURGERY, PROFESSOR, 医学部, 教授 (90150341)
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| Project Period (FY) |
1995 – 1996
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| Project Status |
Completed (Fiscal Year 1996)
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| Budget Amount *help |
¥2,200,000 (Direct Cost: ¥2,200,000)
Fiscal Year 1996: ¥1,000,000 (Direct Cost: ¥1,000,000)
Fiscal Year 1995: ¥1,200,000 (Direct Cost: ¥1,200,000)
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| Keywords | CALPAIN / PROTEIN KINASE C / DELAYED NEURONAL DEATH / PKC |
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| Research Abstract |
Immunohistochemical and biochemical analyses were performed to clarify the relationship of calpain and protein kinase C (PKC) on the development of delayed neuronal death after transient global ischemia in rats. The immunoreactivity of microtuble associated protein (MAP) 2 was decreased in the CA1 subfield of hippocampus from 3 days after the induction of global ischemia. MAP2 degradation was preceded by the spectrin breakdawn, that is, the breakdown of spectrin ocurred 1 to 2 days after the ischemia. These results indicate that progressive breakdawn of cytoakeletal proteins was not uniform. Calpain is a calcium-dependent proteolytic enzyme which degradate MAP2 and spectrin. Therefore, The action of calpain on cytoskeletal proteins may differ between its substrates.
Immunoreactivity of calpain was also studied in the same experimental model using polyclonal antibodies against activated forms of μ - or m-calpain. After the induction of transient global ischemia, immunoreactivities for μ
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- and m-calpain was increased in the apical dendrites, perikarya and nuclei of the pyramidal cells of hippocampal CA1 region 3 days after the ischemia. These cells resulted in delayed neuronal death. After 7 days, almost all of the pyramidal cells showed necrosis and slight immunoreactivity of calpain remained in nuclei. No apparent change of immunoreactivity for calpain was shown in neuronal cells in another hippocampal region. The immunoreactivity of γ -PKC was strongly positive in the apical dendrites and cell body of the pyramidal cells of hippocampal CA1 region 1 to 2 days after the ischemia. From 3 days after the ischemia, the immunoreactivity of γ -PKC was extensively lost in the same region. Administration of the antagonist against calpain before induction of the global ischemia suppressed the development of delayed neuronal death. Western blot analysis of calpain showed the decrease of membranous fraction in comparison with soluble fraction prepared from the CA 1 sector 3 days after the ischemia. The antagonist did not have influence on the immunohistochemical localization and activity of γ -PKC. Administration of the antagonist against PKC before induction of the global ischemia suppressed the development of delayed neuronal death. Increasing of immunoreactivity for PKC was not observed in the CA1 subfield 1 to 2 days after the ischemia. The antagonist against PKC did not have influence on the activity and the subcellular localization of calpain in the hippocampus after the ischemia.
These results may indicate that activation of PKC precede the activation of calpain and the PKC may be activated 1 to 2 days after the ischemia when the activation of calpain with structural change never ocur. The delayed activation of calpain may contribute to the cytoskeletal degradation of CA1 neurons after the ischemia. It is suggested that the delayed neuronal death may develop by the PKC activation which is not always dependent on the calpain activation. Less
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