1998 Fiscal Year Final Research Report Summary
Microglial activation and blood-brain barrier function in ischemia-related neuronal death
| Project/Area Number |
09670095
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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 |
General pharmacology
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| Research Institution | NAGASAKI UNIVERSITY |
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Principal Investigator |
NIWA Masami School of Medicine, Nagasaki University, Professor, 医学部, 教授 (20136641)
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| Co-Investigator(Kenkyū-buntansha) |
NAGAYAMA Yuji School of Medicine, Nagasaki University, Lecturer, 医学部, 講師 (30274632)
SHIGEMATSU Kazuto School of Medicine, Nagasaki University, Associate Professor, 医学部, 助教授 (20154205)
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| Project Period (FY) |
1997 – 1998
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| Keywords | ischemia-related neuronal death / microglia / endothelin / endothelin receptor / blood-brain barrier / MCP-1 / vascular endothelial growth factor / hippocampus CA1 neurons |
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| Research Abstract |
We studied the pathophysiological significance of the blood-brain barrier function and microglial activation on our animal model of delayed neuronal death, based on the hypothesis that microglia across the damaged BBB is activated by monocyte chemotactic protein (MICP)-l produced by brain capillary endothelial cells, a main composer of the BBB, and the damaged BBB stimulates microglia with endothelin ET_B receptor to secrete vascular endothelial growth factor (VEGF) , a repair factor for the BBB.To test the hypothesis, we used our newly-developed method for analyzing the receptor dynamics ; the quantitative receptor-imaging system with three experimental techniques, 1) in vitro radioligand-binding technique for functional sites of receptors with ^1^2^51-MCP-I and ^1^2^5I-hVEGF.2) quantitative radioimmunohistochemical technique for sites of receptor proteins maturation with anti-MCP-1 and anti-hVEGF antibodies, and 3) in situ hybridization technique for production sites of receptors with ^3^5S-cRNA probes of MCP-l and VEGF receptors genes. At 7 days after transient forebrain ischemia, a time when neuronal death in the hippocampus CAl pyramidal cell layer occurred, the quantitative receptor autoradiographic method we used revealed a dramatic increase in number of ^1^2^5I-MCP-l binding sites. The de novo binding sites appeared in the area corresponding anatomically to the pyramidal cell layer with neuronal death and microglial aggregation. No changes were observed at 2 and 5 days after occlusion. Also, the de novo ^1^2^5I-hVEGF binding sites were detected in the area with a rich capillary in the CA I hippocampus area at 7 days after a transient forebrain ischemia. Taken together with the expression of MCP- I and VEGF receptor mRNA, we tentatively conclude that a dysfunction in the BBB occurs just before neuronal death and is closely related to microglial activation due to MCP-1.
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