1999 Fiscal Year Final Research Report Summary
PRECONDITIONING EFFECTS ON LTP INDUCTION IN HIPPOCAMPAL CA1 NEURONS
Project/Area Number |
10680738
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Research Category |
Grant-in-Aid for Scientific Research (C)
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Allocation Type | Single-year Grants |
Section | 一般 |
Research Field |
Neuroscience in general
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Research Institution | YAMAGATA UNIVERSITY |
Principal Investigator |
FUJIII Satoshi DEPARTMENT OF PHYSIOLOGY, SCHOOL OF MEDICINE, YAMAGATA UNIVERSITY, RESEARCH ASSOCIATE, 医学部, 助手 (80173384)
|
Project Period (FY) |
1998 – 1999
|
Keywords | LONG-TERM POTENTIAION / PRECONDITIONING / SUPPRESSION OF LTP INDUCTION / IP3 RECEPTORS / SYNAPTIC PLASTICITY / NMDA RECEPTORS / イノシトール3燐酸 / NMDA受容体 |
Research Abstract |
A train of low-frequency afferent stimuli (LFS, 1 Hz, 1,000 pulses), given 60 min prior to a tetanus (100 Hz, 100 pulses), suppresses the induction of long-term potentiation (LTP suppression). Firstly, we investigated the effects of NMDA receptor antagonist (AP5) and adenosine A2 receptor antagonist (CP-66713), respectively, on LTP suppression in CA1 neurons of guinea pig hippocampal slices. When the LFS was delivered in the presence of AP5 (50 μM) or CP-66713 (10 μM), LTP suppression was inhibited, leading to successful LTP induction. Since activation of the adenosine A2 receptors facilitates CaィイD12+ィエD1 influx through the NMDA receptors, this result indicates that CaィイD12+ィエD1 influx through the NMDA receptors is essential for the mechanism of LTP suppression. Secondly, we studied the intracellular CaィイD12+ィエD1 concentration ([CaィイD12+ィエD1]i ) during LTP induction at CA1 pyramidal neurons of mice lacking type 1 inositol-1, 4, 5-triphosphate receptors (IP3R1). The IP3 receptor acts as a channel of IP3-gated CaィイD12+ィエD1 release from intracellular calcium storage in hippocampal neurons. LTP suppression was not induced in CA1 neurons of mice lacing IP3R1, where [CaィイD12+ィエD1]i decrease during LTP induction was slower than in CA1 neurons of control wild-type mice. These indicate that LTP suppression in hippocampal CA1 neurons depends on both CaィイD12+ィエD1 influx through NMDA receptors and CaィイD12+ィエD1 efflux through IP3R1 during pre-conditioning LFSs. Then, it is possible that post-synaptic CaィイD12+ィエD1 efflux through IP3R1 during, or after, LFS, as well as CaィイD12+ィエD1 influx from the extracellular space, triggers signaling steps to quicken [CaィイD12+ィエD1]i decrease during LTP induction.
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Research Products
(2 results)
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[Publications] Fujii, S., Kuroda, Y., Ito, K.-I., Yoshida, M., Kaneko, K., Yamazaki, Y., Sasaki, H., Kato, H.: "Endogenous adenosine regulates the effects of low-frequency stimulation on the induction of long-term potentiation in CA1 neurons of guinea pig hippocampla slices."Neuroscience Letters. 279(2). 121-124 (2000)
Description
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