| Budget Amount *help |
¥3,200,000 (Direct Cost: ¥3,200,000)
Fiscal Year 1999: ¥1,300,000 (Direct Cost: ¥1,300,000)
Fiscal Year 1998: ¥1,900,000 (Direct Cost: ¥1,900,000)
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| Research Abstract |
It has been shown that autologous nucleus pulposus relocated on the lumbar nerve root in rats produces time dependent and reversible mechanical hyperalgesia which is thought to be an pain related behavior in peripheral neuropathic pain models. The purpose of this study were to examine the roles of leukocyte and biologically active substances including in the arachidonic acid cascade in pathophysiological mechanisms of radicular pain induced by the herniated nucleus pulposus. In rats with nitorgen mustard induced lekocytopenia, the nucleus pulposus produced neither mechanical hyperalgesia nor abundant inflammatory cells. Neuropathic pain produced by the nucleus pulposus, when placed on the nerve root, may be related to inflammatory cell infiltration induced by relocation of the nerve root, may be related to inflammatory cell infiltration induced by relocation of the nucleus pulposus rather than the nucleus pulposus it self. Biologically active substances such as prostaglandins, thrombox
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anes, leukotriences, and cyclooxygenase-2 (COX-2) which are metabolites involved in the arachidonic a acid cascade, are detected in herniated disc samples obtained from patients with lumbar disc herniation. Thromboxane AィイD22ィエD2 (TXAィイD22ィエD2) synthase inhibitor, leukotriene BィイD24ィエD2 (LTBィイD24ィエD2) receptor antagonist and COX-2 inhibitor, which were injected into the epidural space, resulted in decrease of mechanical hyperalgesia 3 and 7 days after epidural injection. Inflammatory reactions and granulation tissue were less pronounced 7 days after the epidural injection. It is possible that TXAィイD22ィエD2 LTBィイD24ィエD2 and COX-2, which are produced in the inflammatory cells around the nerve root, play a significant role in mechanical hyperalgesia induced by application of nucleus pulposus on the nerve root in the rat. Epidural injection of LTBィイD24ィエD2 receptor antagonist, TXAィイD22ィエD2 synthase inhibitor and/or COX-2 inhibitor may be therapeutically useful, and may attenuate painful radiculopathy due to lumbar disc herniation. Less
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