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Objective: To investigate the analgesic mechanism of cinobufagin in rats with bone cancer pain. Methods: Female SD rats meeting the conditions of pain threshold were selected to construct cancer-induced bone pain (CIBP) model. On the 7th day after modeling, the sham group and the model group were administrated by saline, while the treatment groups were administrated with the low, medium and high concentrations of cinobufagin for consecutive 7 d. The pain behavior (mechanical withdrawal threshold and thermal pain threshold) was tested before modeling and after modeling, and single injection of cinobufagin after 0.5, 1, 2, 4, 6, 8 and 24 h at the first day. The expression of MAPKs protein was detected by Western Blotting, and the content of spinal cytokines (IL-1β, TNF-α, MCP-1) was detected by ELISA. Results: The mechanical pain threshold and thermal pain threshold were significantly decreased in the model group, compared with the sham group (P 0.05). Protein levels of MAPKs were increased in the model group, while the levels of JNK and p38 were decreased in the cinobufagin group (P 0.05). ELISA results showed that cinobufagin significantly decreased the content of cytokines in the spinal cord, when compared with the model group (P < 0.05). Conclusion: Cinobufagin can inhibit the expression of MAPKs proteins in the spinal cord of the rat model with bone cancer pain, ultimately decrease the content of IL-1β, TNF-α, and MCP-1 to alleviate the pain during the process of cancer pain.
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Aim: To study the effects of the fatigue-predominant subhealth on mechanical and thermal pain sensitivity in mice. Methods: Kunming mice were randomly divided into two groups (n = 10); normal control group (control), fatigue-predominant subhealth model group (fatigue). The physiological behavior, rota-rod test and blood routine indexes were examined. The paw withdrawal mechanical threshold (PWMT) and the paw withdrawal thermal latency (PWTL) were measured in order to reflect the change of the mechanical and thermal pain sensitivity. Results: Compared to control group, the fur of model group was markedly pale, the time of rota-rod test was significantly lower (P < 0. 01), the data of blood cells was nearly the same, the outcome of PWMT was increased (P < 0. 01), and PWTL was decreased (P < 0. 01). Conclusions The fatigue-predominant subhealth reduces the mechanical pain sensitivity and increases the thermal pain sensitivity in mice.
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Objective To observe the effects of repeated low and high-frequency transcranial magnetic stimulation (rTMS) on neuropathic pain and the expression of specific activation markers of astrocytes and glial fibrillary acidic protein (GFAP) in the lumbar spinal cord.Methods Twenty-eight male Sprague-Dawley rats were randomly divided into a sham-operated group,a sham-rTMS group,a 1 Hz group and a 20 Hz group,with 7 in each group.The rats in the sham-operated group had their sciatic nerve exposed without ligation,while the other groups underwent sciatic nerve ligation to induce neuropathic pain.Three days after the operation,rTMS was applied to the primary motor cortex (M1) contralateral to the pain once a day for 10 consecutive days.Pain-related behavior and thermal pain response were tested before the operation and before and after the course of rTMS therapy.The expression of GFAP in the lumbar spinal cord was examined.Results All of the rats which underwent sciatic nerve ligation showed pain-related behavior and significantly decreasing thermal pain latency compared with the sham-operated group.After the rTMS therapy the thermal hyperalgia was significantly attenuated in the 20 Hz group but not in the 1 Hz group compared with the sham-rTMS group.The expression of GFAP in the dorsal horn of the lumbar spinal cord ipsilateral to the neuropathic pain was significantly increased in the sham-rTMS group and the 1 Hz group compared with the sham-operated group.Compared with the sham-rTMS group,GFAP levels were significantly lower in the 20 Hz group but not in the 1 Hz group.The pain relief in the 20 Hz group was negatively related to the expression of GFAP.Conclusions Neuropathic pain induced by peripheral nerve injury is associated with increased activity and proliferation of astrocytes in the dorsal horns of the spinal cord.High-frequency rTMS can relieve neuropathic pain through inhibiting the activity and proliferation of astrocytes in the dorsal horns,but low-frequency rTMS has no clinically significant effect.
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Objective To investigate the role of astrocytes activation in post herpetic neuralgia (PHN). Methods The kunming mice (20-25 g) were used in this study. Resiniferatoxin was injected into the peritoneal cavity.Immunofuorescence was used to detect the activation of astrocytes , mechanical paw withdrawal threshold (MWT)and thermal withdrawal latency (TWL) were used to assay the mechanical allodynia and thermal hyperalgesia, respectively. Fluorocitrate, an inhibitor of astrocytes was intrathecally (i.t.) or intraperitonealy (i. p.) injected into the mice. Results Compared with the vehicle group, MWT was decreased, and TWL was increased significantly in the RTX group. Pre-treatments of fluorocitrate (Fc, i.t.,or i.p.) inhibited the decrease of MWT. Conclusion The activation of astrocytes mediates the post herpetic neuralgia.
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OBJECTIVE: Dorsal root entry zone(DREZ) operation has been the most common surgical treatment for paraplegic pain in the past, but the results differ according to the patients. In this study, we attempt to analyze the results from the patients by the different patterns of the pain before the surgery. METHODS: A total of twelve paraplegic patients have undergone a total of thirteen radiofrequency DREZ coagulation procedures between April 1994, and March 2003. The patients were divided depending on patients' subjective description on the character, frequency, and range of pain. RESULTS: The patients were divided into the two groups, postoperatively: improvement of more than 75% of pain was defined as treatment success, and any level less than 75% of improvement was defined as treatment failure. Eight of the ten mechanical pain group cases were regarded as treatment success, and remaining two cases with thermal type of pain as treatment failure. Also, one case with combined pain failed to obtain any favorable outcome. Intermittent pain group (6 of 7 cases), continuous pain group (2 of 6 cases), and localized pain group (7 of 11 cases) showed treatment success, respectively. However, diffuse pain group (1 of 2 cases) resulted in poor outcome. CONCLUSION: Radiofrequency DREZ coagulation is more effective in managing intermittent and/or mechanical pain than continuous and/or thermal pain in the paraplegic patients following spinal cord injury.
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Humanos , Traumatismos de la Médula Espinal , Raíces Nerviosas Espinales , Insuficiencia del TratamientoRESUMEN
Objective The aim of this paper is to develop a holistic mathematical model to quantify the correlation between skin thermal sensation and noxious stimuli,since skin thermal pain is one of the most common problems in everyday life and the understanding of the underlying physical mechanisms is still not clear.Methods The model is developed by considering the biothermomechanical behaviour of skin tissue and by incorporating the current understanding of biophysical and neurophysiological mechanisms of pain sensation.Results The proposed model consisted of three interconnected sub-models: peripheral modulation of noxious stimuli,which converts the energy from a noxious thermal stimulus into electrical energy via nerve impulses;transmission,which transports these neural signals from the site of transduction in the skin to the spinal cord and brain;and modulation and perception in the spinal cord and brain.The model predictions agree well with existing experimental data.Conclusion With this model,a direct relationship has been built between the level of thermal pain sensation and the character of noxious stimuli.