| Project/Area Number |
18613023
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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 |
Pain science
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| Research Institution | Kansai Medical University |
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Principal Investigator |
ABE Tetsuya Kansai Medical University, Faculty of Medicine, Assistant Professor (20411506)
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| Co-Investigator(Kenkyū-buntansha) |
MATSUMURA Shinji Kansai Medical University, Faculty of Medicine, Assistant Professor (70276393)
FUKUNAGA Mikihiko Kansai Medical University, Faculty of Medicine, Associate Professor (90257949)
NAKAI Yoshihide Kansai Medical Univerity, Faculty of Medicine, Professor (00091281)
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| Project Period (FY) |
2006 – 2007
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| Project Status |
Completed (Fiscal Year 2007)
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| Budget Amount *help |
¥3,910,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥210,000)
Fiscal Year 2007: ¥910,000 (Direct Cost: ¥700,000、Indirect Cost: ¥210,000)
Fiscal Year 2006: ¥3,000,000 (Direct Cost: ¥3,000,000)
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| Keywords | nitric oxide / neuropathic pain / primary afferent / NMDA receptor / spinal cord / enzymohistochemistry / Imaging / mice / 神経因性痺痛 / ノシセプチン |
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| Research Abstract |
We established an ex vivo system to elucidate biochemical and molecular mechanisms for nNOS activation by the use of a combination of isolated intact spinal cord preparations and NADPH-diaphorase histochemistry.
Nociceptin/orphanin FQ (N/OFQ) was earlier shown to be involved in the maintenance of neuropathic pain by activating neuronal nitric oxide synthase (nNOS). We examined the N/OFQ signal pathways coupled to nNOS activation in the spinal cord by using this ex vivo system. N/OFQ enhanced nNOS activity in the superficial layer of the spinal cord, as assessed by NADPH-diaphorase histochemistry, in a time- and dose-dependent manner. The maximum effect was observed at 3-10 nM. The N/OFQ-stimulated nNOS activity was inhibited by NMDA receptor antagonists MK-801 and D-AP5, but not by the NR2B-selective antagonist; and the stimulated activity was observed in NR2D(-/-) mice, but not in NR2A(-/-) or NR2A(-/-)/NR2D(-/-) mice. N/OFQ receptor antagonists attenuated the nNOS activity stimulated
… More
by N/OFQ, but not that by NMDA. N/OFQ stimulated nNOS activity by a biochemical cascade initiated by activation of NMDA receptors containing NR2A.
To clarify whether NO itself affected nNOS activity in the spinal cord as a retrograde messenger, we examined the involvement of the NO/cGMP signaling pathway in the regulation of nNOS activity. NO-generating agents enhanced NADPH-diaphorase staining in the spinal cord 8-Br-cGMP also enhanced it similar to that by NO-generating agents, and 8-Br-cAMP and forskolin, an activator of adenylate cyclase, enhanced it moderately. NO-generating agents markedly increased the cGMP level in the spinal cord. Additionally, the nNOS activation was completely inhibited by NMDA antagonists MK-801 and d-AP5, partially by the NR2B-selective antagonist, and was attenuated in NR2A(-/-) and NR2A(-/-)/2D(-/-) mice. These results suggest that NO may regulate nNOS activity as a retrograde messenger in the spinal cord via activation of NMDA receptor containing NR2A and NR2B subunits. Less
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