| Background:Discogenic pain was a major cause of chronic low back pain which was due to the internal structure of intervertebral disc including nucleus pulposus and annulus fibrosus appeared disorder, and nucleus pulposus leaking to the outer fibrous ring caused low back pain. Now inflammatory mechanisms of the pain were paid more and more attention to. The roles of a variety of cytokines involved in inflammatory pain were unknown in occurrence and development of pain mechanism, and how to use these cytokines to treat pain, has attracted wide research.Currently it was known that NF-kappa B signals transduction pathway was involved in the control of neuropathic pain, the expression of multiple inflammatory mediators, increasing inflammation, causing pain. A variety of inflammatory mediators were regulated by the NF-κB signal transduction pathway that made the expression of inflammatory factors significantly increased, such as interleukin-6 (IL-6), nitric oxide (NO), tumor necrosis factor-α(TNF-α), matrix metalloproteinases (MMPS), prostaglandin-2 (PGE22), phospholipase-2 (PLA-2) and so on. Previous studies reported that the NF-κB signaling pathway was activated in the dorsal root ganglia and spinal dorsal horn as neuropathic pain occurred.However, these experimental animal models in the studies adopted the methods of ligation of sciatic nerve or lumbar nerve roots. The pathophysiological mechanisms of pain produced by mechanical stimulus were different from discogenic pain. In our studies we simulated the pathological form of clinical discogenic pain in order to establish a new animal pain model, and observed the expression of NF-κB and downstream inflammatory mediators in rostroventromedial medulla neurons. Although Kawakami, etc. utilized this model with autologous nucleus pulposus cause pain at the first time, but those studies were only limited to the level of lumbar nerve roots and dorsal root ganglia.It was known that rostroventromedial medulla nuclei (RVM) accepted the incoming signals from prefrontal cortex, hypothalamus, central periaqueductal gray (PAG) and parabrachial nucleus structure and its outgoing fibers primarily went down to reach the spinal cord dorsal horn through the spinal cord dorsal lateral cord and ventral lateral cord, and it consisted of pain transmission pathway. Neurons in rostroventromedial medulla (RVM) are considered to have an important role in mediating descending facilitation in chronic pain states. Nuclear factor-kappa B (NF-κB) is one of the most important transcription factors regulating gene expression of the pro-inflammatory cytokines such as interleukin-6 (IL-6) in the development of many chronic inflammatory diseases.For this model ventromedial medulla oblongata nuclei involved in inflammatory mechanisms for the lack of in-depth research.Pyrrolidine dithiocarbamate (PDTC), a kind of anti-oxidants that effectively blocked the activation of NF-κB in vivo, had been widely applied to inhibit NF-κB activity in previous experiments. By intrathecal administration, expression of NF-κB and inflammatory cytokines related to neuropathic pain was unknown in RVM neuron.Objective:This experiment focused on the incentives of discogenic pain that intervertebral disc degenerated and nucleus pulposus induced immune response; and studied the expression of inflammatory mediators resulting in pain; and researched the relay nuclei (RVM) involved in the control of neuropathic pain pathways. This research approached the regulatory mechanism of NF-κB and downstream inflammatory factors such as IL-6 for discogenic pain involved in rostroventromedial medulla nuclei, with a view to looking for new ways for prevention and treatment of discogenic low back pain.Methods:1. Models and groups:Fifty-six male Sprague-Dawley rats were randomly divided into two groups:surgical group and sham group. First, in surgical group autologous caudal nucleus pulposus was placed on right 4th and 5th lumbar nerve roots. And in sham group nerve roots were only exposed without other management. Preoperatively and postoperatively 1st,4th,7th,14th,28th day mechanical withdrawal threshold and thermal withdrawal latency were measured on bilateral plantar hind paws.2. Immunohistochemistry (IHC):After heart perfusion, the section of RVM was collected and sliced. IHC detected expression of NF-κB and inflammatory factors in the tissues of each group. TJTY-400TC color cell analysis software was applied to calculate the average NF-κB p65 and IL-6 immunoreactive cells in twenty randomly selected visions without overlapping fields.3. Western-blot:When measurement of pain threshold is completed, rats were executed and the sections of RVM were collected. For the results UNSCAN-IT Bio-gel electrophoresis image analysis system was used for Western-blot measurement with immunoreactive bands for the absorbance measurement. The absorbance ratio of NF-kappaB andβ-actin bands represented the relative expression levels of NF-kappaB.4. Statistical analysis:The SPSS 13.0 was used for dataanlysis. When P<0.05 there was significant difference between groups.Results:1. Mechanical withdrawal threshold and thermal withdrawal latency in each group: Preoperatively there was no statistical significance in mechanical withdrawal threshold and thermal withdrawal latency between two groups. the injured side demonstrated significantly worse mechanical and thermal hyperalgesia related to neuropathic pain. After the first 1～3 d, no significant difference was found in mechanical withdrawal threshold and thermal withdrawal latency between two groups. Surgery group:in the right side threshold values decreased on the 4th day, and reached their peak on the 7th day, and then began to gradually recover, and abnormal values continued to the 28th day. Compared with the Sham group there were significant difference on each time point (P<.05). In surgery group, there was significant difference between the left and right side of same rat on 4th d,7th d,14th d (P<.05). In sham group there were no statistical differences between two lefts of same rat preoperatively and postoperatively (P>.05).2. Western-blot results:Surgical group, the expression of NF-kappa B began to increase on 4th day, and reached the summit on 7th day, and then started to restore, and higher expression continued for 28 days. Sham group, the expression of NF-kappa B did not changed significantly preoperatively and postoperatively. The patterns of behavioral changes were correlated with histologic changes in RVM neurons. There was significantly difference between two groups postoperatively (P<.05),3. Immunohistochemical results:there were fewer NF-kappa B positive cells in sham-operated group than those in surgical group, and significant difference was found between two groups according to the value of immunoreactive cells (P <.05); inflammatory cytokines IL-6 also showed the same trend.Conclusion:1. In this study neuropathic pain model was mostly similar with the mechanism of clinical neuropathic pain and better explain clinical problem. The results indicate that NF-κB in the RVM is involved in triggering the enhanced sensitivity to stimulation induced by by application of nucleus pulposus. The results of this study could be reproduced.2. NF-κB signaling transduction pathway played an important role in inflammatory pain, and regulated the expression of inflammatory factors such as IL-6. It showed that NF-κB signaling transduction pathway and the downstream inflammatory cytokines may be involved in the regulation of neuropathic pain.3. Medulla rostroventromedial medulla nucleus was a relay station involved in the conduction process of neuropathic pain,.suggesting that NF-κB inhibitors can control the pain signal transduction through the neurons. Objective:In this study, PDTC was used by intrathecal administration in order to inhibit expression of NF-κB. We observed NF-κB and downstream inflammatory factor IL-6 levels in the rostral ventromedial nuclei and the spinal dorsal horn neurons. The goal of this part was to determine NF-κB role in neuropathic pain modulation.Methods:5. Intrathecal catherization and groups:after anesthesia, atlanto-occipital membrane was exposed, PE-10 catheter was intrathecally placed. This progress was successful as cerebrospinal fluid flowed along the catheter. Fixed catheter and suture the wound. Excluding the rats with motor dysfunction. The rats were fed in single cage and then were used for further experiments after five days. Thirty-two rats with catheter were divided into four groups:surgery+saline group, surgery+ PDTC group, sham+saline group, sham+PDTC group.6. After intrathecal injection, surgery or sham pain models were taken on the following day. Preoperatively and postoperatively, mechanical withdrawal threshold and thermal withdrawal latency were measured before administration. After continuous 7-days infusion, the rats were executed and the samples were collected for further experimental test.7. Immunohistochemistry (IHC):IHC detected expression of NF-κB and inflammatory factors in the tissues of each group, in order to explore the effect of PDTC on expression of NF-κB.8. Western-blot:UNSCAN-IT Bio-gel electrophoresis image analysis system was used for Western-blot measurement with immunoreactive bands for the absorbance measurement. The absorbance ratio of NF-kappaB andβ-actin bands represented the relative expression levels of NF-kappaB.9. Statistical analysis:The SPSS13.0 was used for dataanlysis. When P<0.05 there was significant difference between groups.Results:4. After intrathecal administration of PDTC, the values of mechanical withdrawal threshold and thermal withdrawal latency were higher in operation+PDTC group than those in operation+saline group, with statistically significant difference (P<.05). For Sham-operated+saline group and sham+PDTC group, there was no significant difference (P>.05) in mechanical withdrawal threshold and thermal withdrawal latency.5. Western-blot results:After intrathecal administration, the expression of NF-kappa B in PDTC+operation group showed significantly different compared with operation group (P<.05).6. Immunohistochemical results:After intrathecal administration, PDTC+operation group, NF-kappa B positive cells significantly increased compared with surgery alone (P<.05). PDTC+sham group and sham+saline group were not changed significantly (P>.05). The inflammatory cytokines IL-6 also showed the same trend.Conclusion:1. Intrathecal administration was a safe and reliable administration method, and this method could be sustained and regulated to delivery.2. Intrathecal injection of PDTC significantly inhibited the symptom of neuropathic pain rats.3. PDTC could inhibit the activation of NF-κB in RVM and dorsal horn region of and reduce pro-inflammatory cytokines IL-6 expression in neuropathic pain model, suggesting that NF-κB signaling pathway participated in the regulation of neuropathic pain.4.Blocking NF-κB signal transduction pathway might be an effective prevention and treatment of neuropathic pain. Objective:To appraise the outcomes of standard discectomy and discectomy combined with interbody fusion and fixation for the patients with lumbar disc herniation, and evaluate the advantages of two treatments.Methods:We studied 82 cases of lumbar disc herniation which involved single segment (L4/5 44 cases, L5/6 38 cases).The age of patients ranged from 35 to 67 years old (average 44.6±10.4 years old),49 male patients and 3,3 female patients. The patients were randomly treated by standard discectomy (44 cases,42.2±8.5 years old) or discectomy combined with interbody fusion and fixation (38 cases,46.8±10.8 years old). Postoperatively we assessed the effects of two surgical methods according to JOA scores and ODI index. The results were compared between JOA and intervertebral disc height loss. The results were analyzed by SPSS statistical software, P<0.05 was considered statistically significant.Results:On the basis of JOA scores and ODI index, the patients in standard discectomy group and fixation group significantly relieved, there was statistical difference preoperatively and postoperatively (P<0.05). There was no significant difference at each time preoperatively and postoperatively between two groups (P>0.05). According to the rate of intervertebral height changes, there was no significant difference preoperatively and postoperatively in standard discectomy group (P>0.05); there were statistically significant preoperatively and postoperatively in fixation group (P<0.05). And the relation of JOA scores and the intervertebral disc height changes were compared according to height ratio (less than 75%group and more than 75% group), JOA score disc in patients of height ratio> 75% was significantly higher than the patients of height ratio<75%, and significant difference was found (Student t test, P<0.05). The patients with more BMI had higher recurrence rate of lumbar disc herniation. It concluded that height loss of intervetebral disc was closely related to the outcome of surgical management.Conclusions1. Both standard discectomy and discectomy combined with interbody fusion and fixation received satisfactory results in the short term follow-up. There was no significant difference according to postoperative outcomes in two methods.2. There was significant correlation between loss of intervetebral height with clinical symptoms in standard discectomy group.3. A higher recurrence rate was found after standard discectomy surgery.4. Treatment options were strictly selected for the patients with lumbar disc herniation in accordance with the surgical principle. Excessive fusion should be avoided.
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