Annals of Rehabilitation Medicine

The Long-Lasting Pattern of the Neuropathic Radicular Pain in An Autologous Nucleus Pulposus Model of Rat.: Kim, Wook Ro , Ahn, Sang Ho , Cho, Yun Woo , Cho, Hee Kyung , Kim, Han Seon , Kim, Su Jeong , Seo, Jeong Min; J Korean Acad Rehabil Med 2009;33(4):477-482.

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Objective
To observe the long-lasting changes of pain progression with time course in an autologous nucleus pulposus model of rat. Method: The subjects were 25 Sprague-Dawley (Sprague- Dawley, 250 gm) male rats. They were randomly assigned into either the sham or experimental group. In the experimental group (n=15), autologous nucleus pulposus was harvested from the coccygeal intervertebral disc of the rat and this was grafted on the left L5 dorsal root ganglion. In the sham group (n=10), the left L4 and L5 nerve roots were exposed by laminectomy, but the nucleus pulposus was not grafted. All the rats were evaluated for mechanical allodynia and thermal hyperalgesia at 2 days before surgery, and on days 1, 5, 10, 20, 30, 40 and 50 after surgery. The morphological changes of the spinal nerves were assessed by toluidine blue staining on days 5 after surgery. Results: In the ipsilateral hindpaw of the experimental group, there was a dramatic drop of the mechanical withdrawal threshold and the thermal withdrawal latency on day 1 after surgery, which was maintained at day 50 after surgery. In morphological study, pathological findings such as swelling of the myelin sheath, demyelination, swelling and degeneration of the axoplasm were observed in the spinal nerve at day 5 after surgery. Conclusion: The long-lasting pattern of neuropathic radicular pain shown in a rat model of lumbar disc herniations is helpful to understand the natural history of neuropathic radicular pain due to ruptured nucleus pulposus. (J Korean Acad Rehab Med 2009; 33: 477-482)

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Expression of Growth Factors and Cytokines in Patients withDegenerated Disc Disease and Herniated Nucleus Pulposus.: Moon, Chan Sam , Lee, Seung Cheol , Jung, Woon Won , Sul, Donggeun , Hong, Young Ki , Kim, Hyun Sook , Wang, Joonho , Lee, Sang Heon; J Korean Acad Rehabil Med 2009;33(3):304-308.

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Objective
To investigate the expression of cytokines and growth factors in disc specimens obtained from small numbers of patients with herniated nucleus pulposus (HNP) and degenerated disc disease (DDD). Method: A total of ten human intervertebral disc samples consisted of five painful degenerative discs and five herniated intervertebal discs were obtained from surgery. MRI and Western blot analyses on these disc samples were performed to determine the levels of disc degeneration and the expression levels of cytokines and growth factors. Results: The levels of IL-6 were significantly greater in the DDD patients than in the HNP patients, but no statistical differences were observed in the expression of IL-1Ղ, IL-8 and TNF-Ձ between the HNP and DDD patients. In addition, the expression of TGF Ղ was significantly higher in the DDD patients than in the HNP patients. Conclusion: The higher levels of cytokine and growth factor expression in the DDD than in the HNP show why discogenic patients usually have more severe back pain than patients with herniated discs. (J Korean Acad Rehab Med 2009; 33: 304-308)

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The Development of Abnormal Spontaneous Activities in the Experimental Radiculopathy in the Rat.: Han, Tai Ryoon , Lee, Seong Jae , Kwon, Bum Sun , Hyun, Jung Keun , Park, Won Beom; J Korean Acad Rehabil Med 2005;29(4):392-397.

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Objective
Through a animal study using rats, we investigated whether abnormal spontaneous activities (ASAs) could be observed in the radiculopathies of biochemical and mechanical model. Method: A total of 30 Sprague-Dawley male rats were randomly assigned into sham, nucleus pulposus (NP) and ligation groups. In the sham group, the right L4 and L5 nerve roots were exposed by laminectomies. In the NP group, nucleus pulposus was transplanted onto nerve roots from tail. In the ligation group, exposed nerve roots were ligated by silk ligatures. All rats were evaluated by mechanical allodynia, motor paresis, and the needle electromyography (EMG) examination. Results: Mechanical allodynia was observed on the 4th and 7th postoperative days in NP and ligation groups. Motor paresis was observed only in the ligation group. The needle EMG showed ASAs on the 4th postoperative day, but decreased in incidence and amount on the 7th postoperative day in the NP and ligation groups. Conclusion: The ASAs can be observed by the biochemical action of nucleus pulposus as well as the mechanical compression. The results of this study may help explain the discrepancy between radiologic and electrodiagnostic findings. (J Korean Acad Rehab Med 2005; 29: 392-397)

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The Role of Nitric Oxide in Neuropathic Changes Induced by the Autograft of Nucleus Pulposus to the Sciatic Nerve in Rats.: Han, Tai Ryoon , Lee, Jong Min , Choi, Jong Chul , Kim, Jung Ran; J Korean Acad Rehabil Med 2001;25(4):653-665.

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Objective: To investigate the neuropathic changes induced by nucleus pulposus and possible role of nitric oxide (NO) in the pathogenesis of painful radiculopathy.

Method: Autologous nucleus pulposus was harvested from the rat coccygeal intervertebral disc and grafted to the sciatic nerve. Pain behavior, neurophysiologic and pathologic changes were compared between autografted and sham operated group during 14-day-period. Western immunoblotting and immunohistochemistry with anti-nitrotyrosine mouse monoclonal antibody were used to compare the NO production and nerve damage in autografted and sham operated nerve tissues.

Results: Mechanical allodynia and thermal hyperalgesia were observed 2 days after autograft of nucleus pulposus and persisted during 14-day-period (p＜0.05). Motor nerve conduction latency was delayed and compound muscle action potential amplitude was decreased 5 days after autograft (p＜0.05). Histologically, nucleus pulposus induced severe inflammatory reaction with fibroblast proliferation and foamy macrophage infiltration, which were persisted during 14-day- period. More nitrated proteins were detected consistently in nerve tissues with autograft of nucleus pulposus and immunohistochemical staining of nitrotyrosine was prominent around foamy macrophages.

Conclusion: These data suggest that nucleus pulposus induce mechanical allodynia, thermal hyperalgesia and nerve dysfunction through inflammatory reaction with macrophage infiltration. NO and NO related tissue injury may play an important role in the pathogenesis of painful radiculopathy.