2010 Fiscal Year Final Research Report
Dentate neurogenesis and neural maturation in animal models of epilepsy
| Project/Area Number |
20591722
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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 | Juntendo University |
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Principal Investigator |
NAKAJIMA Madoka Juntendo University, 医学部, 助教 (50317450)
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| Co-Investigator(Kenkyū-buntansha) |
菅野 秀宣 順天堂大学, 医学部, 准教授 (90265992)
西村 欣也 順天堂大学, 医学部, 先任准教授 (80164581)
新井 一 順天堂大学, 医学部, 教授 (70167229)
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| Project Period (FY) |
2008 – 2010
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| Keywords | 再生医学 / 神経科学 |
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| Research Abstract |
【Purpose】Neuronal regeneration is thought to be induced by stimulation from ischemia or epileptic seizures, as well as to compensate for neuronal necrosis or apoptosis from such insults. It is also said that neuronal regeneration is a cause of hippocampal epileptogenesis, although much is unknown about the turnover mechanism or significance of newly formed neurons. Using an animal model in which epileptic seizures were induced by pilocarpine, changes in hippocampal neurogenesis with time brought about by epilepsy were investigated using immunostaining and electrophysiological (patch-clamp) techniques. The role of hippocampal neurogenesis in epileptogenesis was then examined.
【Methods】Forty-eight hours after epileptic seizures were induced by intraperitoneal injection of pilocarpine in C57/BL mice, the hippocampus was injected with a green fluorescent protein (GFP) using a retrovirus. Thus, new nerves induced by the epileptic seizure were marked with GFP. Immunostaining was done 7 days (
… More
1 week), 14 days (2 weeks), and 28 days (4 weeks), 6 months after status epilepticus, and the degree of maturation of normal neurons (NeuN staining), DCX, NeuroD, PSA, BrdU and the proportion of apoptosis (ssDNA staining) were investigated. With the patch-clamp, the firing pattern in the cells marked with GFP was directly recorded to investigate cell excitability.
【Observation results】Many new cells were produced in the subgranule zone after the epileptic seizures, but they were small and fragile, and almost none of the immature GFP-positive cells entered the maturation process. They disappeared by 1-4 weeks after the seizure. The GFP-positive cells that disappeared at an early stage were negative for both ssDNA and NeuN. The GFP-positive cells at 1-2 weeks after the seizure had input resistances (IRs) of 1.2 GΩ-2.0 GΩ and resting membrane potentials (RMPs) of -55 mV to -70 mV. The GFP-positive cells at 4 weeks had IRs of 300 MΩ-1000 MΩ and RMPs of -70 mV to -80 mV. The membrane resistance in the new neurons induced by epilepsy was higher in the less mature cells, and they had a low firing rate. Less
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