2003 Fiscal Year Final Research Report Summary
Study of nociceptive transduction pathways derived from the lumbar spine.
| Project/Area Number |
14571358
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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 |
Orthopaedic surgery
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| Research Institution | Chiba University |
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Principal Investigator |
TAKAHASHI Kazuhisa Chiba University, Graduate School of Medicine, Associate Professor, 大学院・医学研究院, 助教授 (20179477)
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| Project Period (FY) |
2002 – 2003
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| Keywords | Discogenic pain / Neurotracer / Dorsal root ganglion / Sympathetic trunks / Neurotrophic factor |
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| Research Abstract |
Previously, it was believed that the lumbar intervertebral disc was innervated segmentally by dorsal root ganglion (DRG) neurons via the sinuvertebral nerves. Using retrograde tracing methods, we clarified that the lower disc (L5-L6) is innervated predominantly by upper (L1 and L2) DRG neurons via the sympathetic trunks. Furthermore, we investigated the expression of various pain-related molecules such as substance P (SP), calcitonin gene-related peptide (CGRP), isolectin B4 (IB4), P2X_3 receptor and using a combination of immunostaining with the retrograde tracing method We found that about half of the neurons innervating the disc were SP-and CGRP-immunoreactive (-ir), whilst, only a small proportion of the DRG neurons innervating the disc were IB4-and P2Xrpositive, indicating that peptidecontaining DRG neurons ate the main subpopulation which transmits and modulates nociceptive information from the disc.
Bennett et al. reported that the proportions of CGRP-ir and IB4-binding neurons are different among cutaneous and visceral primary sensory neurons in the rat. They concluded that the proportion of CGRP-ir neurons was higher in visceral afferents, and the proportion of the IB4-binding neurons was lower in visceral afferents than in cutaneous afferents. Thus, the lumbar intervertebral disc had similar neural profiles to that of visceral organs with regard to the proparions of the two types of DRG neurons. However, the proportion of 1B4-biding neurons is dramatically lower in the disc afferents than cutaneous and visceral afferents. Since CGRP-ir and 1B4-binding neurons are thought to be NGF-and GDNF-sensitive neurons respectively, we suppose that nociceptive information from the lumbar intervertebral disc is mainly transmitted and modulated by NGF-sensitive neurons.
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