| Budget Amount *help |
¥4,240,000 (Direct Cost: ¥3,700,000、Indirect Cost: ¥540,000)
Fiscal Year 2007: ¥2,340,000 (Direct Cost: ¥1,800,000、Indirect Cost: ¥540,000)
Fiscal Year 2006: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
INTRODUCTION: The NG2 proteoglycan (NG2), a trans-membrane proteoglycan with a large extracellular domain, has been shown to bind type VI collagen, which is a main constituent of the pericellular matrix in articular cartilage. NG2 has been reported to play an important role as an interactive extracellular matrix component and membrane receptor for growth factors. Importantly, NG2 proteoglycan has also attracted much attention among researchers who investigate the nervous system; because NG2 has been shown to strongly regulate nerve growth. Therefore, we hypothesized that the expression of NG2 contributes to the pathogenesis of intervertebral disc (IVD) degeneration, and play an important role in the regulatory mechanism of a 'discogenic low back pain'.
RESULTS: [2006] NG2 immunoreactivity co-localized with type VI collagen was found at the periphery of the cell in a ring-like pattern by human IVD cells. The expression of NG2 was identified both by Western blot and RT-PCR analyses. The content of NG2 in human intervertebral disc tissues was elevated in tissues with an advanced stage of degeneration compared to tissues with an early stage of degeneration. [2007] NG2, co-localized with nociceptor fiber (C-fiber), was clearly identified in the rat sciatic nerve. In the target organ such as foot pad and intervertebral disc tissue, the co-localization of NG2 and C-fiber was also found. Furthermore, the expression of NG2 was found to be up-regulated after peripheral nerve injury.
DISCUSSION: The nociceptor fiber, which is involved in the pathogenesis of 'discogenic low back pain', co-localized with NG2 proteoglycan. Interestingly, NG2 is also expressed by intervertebral disc cells, and its expression was up-regulated with the advance of IVD degeneration. Our results suggest the possibility that the change of NW expression within the IVD may have relevance to the regulatory mechanism of "discogenic low back pain
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