Role of spinal cord TNF-α in the development of bone cancer pain in mice

Objective To investigate the role of spinal cord TNF-a in the development of bone cancer pain in mice. Methods Seventy-two 4-6 week old C3H/He mice weighing 18-25 g were randomly divided into 3 groups (n = 24 each) : group I sham operation (group S) ; group II bone cancer pain (group BCP) and group Ⅲ etanercept (group E). Bone cancer pain was induced by implantation of osteosarcoma NCTC 2472 cells into the intramedullary space of right femur in group II and Ⅲ . Group Ⅲ received intraperitoneal etanercept 100 μg at 3 days before and immediately before and day 3 and 6 after tumor cell inoculation. In group S culture medium α-MEM containing no cancer cell was injected instead. The paw withdrawal threshold to mechanical stimuli (PWMT) and paw withdrawal latency to thermal stimuli ( PWTL) were measured before inoculation (baseline) and at day 3, 5,7, 10, 14 after inoculation respectively. Eight animals were killed on the 7th, 10th, and 14th day after inoculation in each group. The spinal cords were removed and TNF-α mRNA expression in the spinal cord was determined by RT-PCR. Results Cancer pain was significantly attenuated by pretreatment with etanercept. The TNF-α mRNA expression in the spinal cord was significantly increased after inoculation and was significantly attenuated by pretreatment with etanercept in group Ⅲ . Conclusion Spinal cord TNF-a is involved in the development of bone cancer pain in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

脊髓胶质细胞在小鼠骨癌痛形成中的作用

Objective To evaluate the role of gliocyte in the spinal cord in the development of bone cancer pain (BCP) in mice. Methods Forty male C3H/He mice aged 8-10 weeks weighing 18-22 g were randomly divided into 4 groups ( n = 10 each) : group I sham operation (group S) , group II BCP, group Ⅲ PBS and group IV minocyline (group M) . In group BCP, PBS and M, bone cancer pain was produced by injection of NCTC2472 fibrosarcoma cell suspension (2 x 105 cells) 10 μl into medullary cavity of calcaneus bone, while in group S, PBS solution 10 μl was injected instead of cancer cell suspension. In group PBS and M, PBS 5 μl and minocyline 5 μl (dissolved to 0.2 mmol/L in PBS)_were given IT immediately before cancer cell inoculation once a day for 11 consecutive days respectively. Mechanical pain threshold was measured at 1 d before cancer cell inoculation, and at 0, 3, 5, 7, 9 and 11d after cancer cell inoculation. Cold pain threshold was measured at 3, 7, 9 and 11d after cancer cell inoculation. The animals were killed after measurement of pain threshold and L4-6, segment of spinal cord was removed for determination of GFAP and CD11b expression by Western blot. Results Compared with group S, mechanical pain threshold was significantly increased at 3-11 d after cancer cell inoculation in group BCP and PBS, and at 3 and S d after cancer cell inoculation in group M, and cold pain threshold was significantly increased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was up-regulated in group BCP, PBS and M ( P < 0.05) . Compared with group BCP, mechanical pain threshold was significantly decreased at 3-11 d after cancer cell inoculation, cold pain threshold was significantly decreased at 7-11 d after cancer cell inoculation, and expression of CD11b and GFAP was down-regulated in group M ( P <0.05) . ConclusionThe activiton of gliocyte in the spinal cord is involved in the development of bone cancer pian in mice.     

The role of N--methy--D--aspartate receptor subunit NR2B in the spinal cord in cancer pain

Cancer pain is one kind of the most common and severe chronic pain. The mechanisms and therapeutics of cancer pain have not achieved a breakthrough yet. Based on the well established involvement of NMDA （N-methy-d-aspartate） receptor containing NR2B in inflammatory pain and neuropathic pain and the effective pain relief by ketamine in cancer patients with intractable pain, we supposed that NR2B in the spinal cord was an important factor in cancer pain. In this study, the possible role played by NR2B in the spinal cord was investigated in mouse model of bone cancer pain. Osteosarcoma NCTC 2472 cells were implanted into the intramedullary space of the right femurs of mice to induce ongoing bone cancer related pain behaviors. At day 14 after operation, the expression of NR2B mRNA and NR2B protein in the spinal cord were higher in tumor-bearing mice compared to the sham mice. Intrathecal administration of 5 and 10 pg of NR2B subunit-specific NMDA receptor antagonist, ifenprodil attenuated cancer-evoked spontaneous pain, thermal hyperalgesia and mechanical allodynia. These results suggest that NR2B in the spinal cord may participate in bone cancer pain of mice, and ifenprodil may be a useful alternative or adjunct therapy for controlling bone cancer pain. The findings may lead to novel strategies for the treatment of bone cancer pain.     

Effects of intrathecal injection of Akt inhibitor Ⅳ on pain behavior in rats model of injected radicular pain

Objective To investigate the effects of intrathecal injection of Akt inhibitor Ⅳ on pain behavior in rats model of injected radicular pain. Methods Eighteen male Sprague Dawley (SD) rats with successful intrathecal intubation were randomly divided into three groups (n=6): Sham group (S), injected radicular pain group (C), and Akt inhibitor group (A). In C group and A group, the model of injected radicular pain were established by surgiflo injection. Akt inhibitorⅣ was injected 30 min before the model preparation in group A. Vehicle (10% ethanol) was intrathecally injected at the same time in group C and group S. Pain ethology indexes such as paw withdrawal mechanical threshold (PWMT) and paw withdrawal thermal latency (PWTL) were assessed on 1 d before and 1, 4, 7, 10, 17 d and 28 d after operation. Results Compared to group S and preoperative level, PWMT and PWTL were decreased on the first postoperative day in group C (P＜0.05). Intrathecal Akt inhibitorⅣ injection significantly decreased PWMT and PWTL (P＜0.05) in groups A. Conclusion Intrathecal Akt inhibitorⅣ injection would intensify pain behavior in rat model of injected radicular pain. Akt may play an important role in the development of pain behavior in rat model of injected radicular pain.     

Increased phosphorylation of cyclic AMP response element binding protein （CREB） in the dorsal root ganglia and superficial dorsal horn neurons following chronic constriction injury

Objective To investigate whether chronic constriction injury （CCI） of the sciatic nerve of rats could produce alterations in the phosphorylation of cyclic AMP response element binding（CREB） protein in dorsal root ganglia （DRG） and superficial dorsal horn neurons of the spinal cord. Methods Chronic constriction injury （CCI） of the sciatic nerve was employed as a model of neuropathic pain. Thirty-two Sprague-Dawley rats were randomly divided into NaYve, Sham, CCI 2w（received CCI for 2 weeks） and CCI 4w（received CCI for 4 weeks） groups. Hind paw withdrawal threshold to mechanical stimuli and withdrawal latency to thermal stimuli were used to detemline the mechanical and thermal hypemlgesia. Then all the rats were deeply anesthetized and perfused intracardiaUy with paraformaldehyde. The fixed I4-5 spinal cord and the L5 DRG ipsilateml to CCI were harvested for fixation. The pCREB-immunoreactive（pCREB-IR） cells in both DRG and superficial dorsal horn neurons were quantified for analysis using immunohistochemistry methods. Results On the 14th day after sciatic nerve injury, all the rats exhibited significant mechanical and thermal hyperalgesia. The mechanical withdrawal thresholds to yon Frey filament from CCI 2w group decreased significantly compared to both baseline values and those of Sham group（ P 〈 0.01 ） ; Thermal withdwal latencies from CCI 2w group decreased significantly compared to both baseline values and those of Sham group（ P 〈 0.01 ）. Some rats from Sham group also showed mechanical hyperalgesia compared to both baseline values and those of Naive group（ P 〈 0.01）. 28 days after CCI, both mechanical and thermal hypersensitivity were significantly alleviated, with no statistical significance compared to those of Sham group. On the 14th day after CCI, the number of pCREB-IR ceils significantly increased in ipsilateral L5 DRGs and superficial dorsal horns（ P 〈 0.01 ） compared to Sham group. The number of phosphorylated CREB-IR cells in the ipsilateral DRGs from Sham group also increased compared to that of Naive rats（ P 〈 0.05）. There were no significant statistical differences of numbers of CREB-IR neuron between Sham group and CCI 4w group. Conclusion CCI increases CREB phosphorylatian both in DRG and superficial dorsal horn neurons of the lumbar spinal cord, and may be one of the key molecular mechanisms of central and peripheral sensitization following peripheral nerve injury.     

鞘内注射DREAM-shRNA对神经病理性痛大鼠脊髓背角p-CREB表达的影响

Objective To investigate the effects of intrathecal (IT) DREAM-short hairpin RNA (DREAM-shRNA) on expression of phosphorylated cyclic AMP response element binding protein (p-CREB) in the spinal dorsal horn in a rat model of neuropathic pain. Methods Adult male SD rats weighing 280-320 g were anesthetized with intraperitoneal 10% chloral hydrate. Neuropathic pain was induced by chronic constrictive injury (CCI) to sciatic nerve. IT catheters were placed according to the method described by Yaksh on 3rd day after CCI. Twenty-four rots in which IT catheter was successfully implanted were randomly divided into 4 groups (n = 6 each) : group Ⅰ sham operation (group S) ; group Ⅱ neuropathic pain (group NP) ; group Ⅲ RNA interference (group RNAi) and group Ⅳ blank vector (group BV). Lentivius with DREAM-shRNA 5 μl was injected IT in group RNAi, and blank vector 5 μl in group BV, and once a day for 7 days, starting from the day 8 after CCI. The mechanical pain threshold was measured at day 1 before CCI (T0 ,baseline) and day 7-14 after CCI (T1-8). The animals were killed on 15th day after CCI. The L4-6 lumbar segment of the spinal cord was removed for determination of the expression of green fluorescent protein (GFP) and p-CREB by immuno-fluorescent method.Results The mechanical pain threshold was significantly decreased as compared with the baseline at T0 in all 4 groups and returned to the baseline levels at T5-8 in group S and RNAi, but remained low in group NP and BY. The mechanical pain threshold was significantly lower after CCI/sham operation and significanty higher at T8 in group RNAi than in the other 3 groups. The expression of p-CREB in the spinal dorsal horn was up-regulated in group NP, RNAi and BV as compared with group S, and in group NP and BV as compared with group RNAi. The green fluorescence was observed in group RNAi but not in the other 3 groups. Conclusion IT DREAM-shRNA can ameliorate neuropathic pain in rats through inhibiting the expression of p-CREB in the spinal dorsal horn.     

大鼠骨癌痛-慢性吗啡耐受模型的建立

目的 建立大鼠骨癌痛-慢性吗啡耐受模型.方法 鞘内置管成功的成年雌性SD大鼠36只,体重180～200 g,采用随机数字表法,将大鼠随机分为3组(n=12):假手术组(S组)、慢性吗啡耐受组(M组)和骨癌痛+慢性吗啡耐受组(BM组).BM组右侧胫骨上段骨髓腔注入Walker256癌细胞10 μl(4×102个细胞/μl)制备骨癌痛模型,M组注射热灭活的Walker256癌细胞10μl,接种后10 d开始鞘内注射吗啡20μg/kg,2次/d,连续9 d.S组仅暴露右侧胫骨上段.分别于接种Walker256癌细胞前、接种后1、3、6、9 d、给予吗啡1、3、5、7、9 d时测定机械缩足阈值(MWT)和机械缩足持续时间(MWD),并于接种后9 d时行放射学检查,进行骨质破坏评分.最后1次测定痛周后,对右侧足底进行触摸刺激,停止刺激后3 h时取脊髓L4-6节段,测定脊髓背角Foa表达水平.结果 与S组比较,M组MWT降低,MWD延长,脊髓背角Fos表达上调(P＜0.05或0.01);与M组比较,BM组MWT降低,骨质破坏评分升高,MWD延长,脊髓背角Fos表达上调(P＜0.05或0.01).结论 成功制备了大鼠骨癌痛-慢性吗啡耐受模型.

Abstract：

Objective To establish a rat model of bone cancer pain-chronic morphine tolerance. Methods Thirty-six adult female Sprague-Dawley rats weighing 180-200 g in which intrathecal catheters were successfully placed without complications were randomly divided into 3 groups ( n = 12 each) :group sham operation (group S),group chronic morphine tolerance (group M) and group bone cancer pain + chronic morphine tolerance (group BM). Bone cancer pain was induced by intra-tibia inoculation of Walker256 mammary gland carcinoma cells (4 ×102 cells/μl) in group BM, while in group M heat-inactivated Walker256 mammary gland carcinoma cells were given instead, and then 10 days later, intrathecal morphine 20 μg,/kg was administered twice a day for 9 consecutive days. The mechanical paw withdrawal threshold (MWT) and mechanical paw withdrawal duration (MWD) were measured before inoculation, at day 1, 3, 6 and 9 after inoculation, and at day 1, 3, 5, 7 and 9 of morphine administration. The degree of bone destruction was assessed by radiological analysis at day 9 after inoculation. After the last measurement of pain threshold, the rats were given innoxious touch-stimulus. The rats were sacrificed 3 h after stopping the stimulus, and L4-6 segment of the spinal cord was isolated to determine the expression of Fos protein in the spinal dorsal horn. Results Compared with group S, MWT was significantly decreased, MWD was significantly prolonged and the expression of Fos protein was up-regulated in group M ( P ＜ 0.05 or 0.01 ). MWT was significantly decreased, MWD was significantly prolonged, bone destruction scores were significantly increased,and the expression of Fos protein was up-regulated in group BM compared with group M ( P ＜ 0.05 or 0.01 ). Conclusion A rat model of bone cancer pain-chronic morphine tolerance is successfully established.     

鞘内注射加巴喷丁和/或吗啡对切口痛大鼠脊髓氨基酸含量的影响

Objective To study the effects of intrathecally administering gabapentin and/or morphine on the amino acid neurotransmitters in spinal cord of rat incision pain models.Methods Forty male SD rats were randomly divided into five groups (n=8) and were intrathecally inserted catheter.Paw incision models were made 5d later.Gabapentin (50 μg,group Ⅲ) or morphine(2.5 μg,group Ⅳ) or both (group Ⅴ) were intrathecally injected 30 min before incision.Another two groups were regarded as shame (group Ⅰ) or control (group Ⅱ).Pain behavior was determined 2 h later using mechanical withdrawal threshold (MWT) and thermal withdrawal latency (TWL).The content of four amino acids including glutamate,aspartate,glycine and γ-aminobutyric acid in rat spinal cord were detected.Results MWT and TWL decreased and the content of glutamate and aspartate in spinal cord increased significantly 2 h after incision(P＜0.05)in groups Ⅱ,Ⅲ and Ⅳ (without statistically differences among three groups),but not in group Ⅴ,compared to them in group Ⅰ.There were no differences in the content of glycine and γ-aminobutyric acid in rat spinal cord 2 h after incision among four groups.Conclusion Intrathecal gabapentin significantly enhances the antinociceptive effect of intrathecal morphine in rat incision pain model,which may owe to the decreased level of excitatory amino acids in spinal cord.     

Involvement of Spinal Cord Nuclear Factor kB Activation in A Rat Model of Persistent,Postoperative Pain Evoked by Skin/Muscle Incision and Retraction （SMIR）

Background： Persistent postoperative pain is common but the pathogenic mechanisms underlying it are under debate. Recent studies have implicated the activation of nuclear factor kappa B （NF-kB） in spinal for development of neuropathic and inflammatory pain. Aims： The aim of the present study was to investigate whether NF-kB also mediates hyperalgesia in persistent postoperative pain and potentially the pathogenesis of postoperative pain, by measuring NF-kB levels and assessing the anti-allodynic effect of NF-r.B inhibition by pyrrolidine dithiocarbamate （PDTC） in rats after skin/muscle incision and retraction （SMIR） injury. Methods： After rats received a SMIR surgery, mechanical allodynia were determined by von Frey filaments, and NF-kB p65 in the spinal cord was quantified to determine the level NF-KB expression at different time points after SMIR by western blotting. The NF-kB inhibitor PDTC was administered intrathecally at day 1 after surgery and then daily for 7 days to determine the role of NF-KB in postoperative pain, Results： A significant increase in level of NF-kB p65 was observed in the spinal cord from day 1 to day 7 after SMIR, Intrathecal injection of PDTC attenuated SMIR-induced mechanical allodynia from day 3 to day 12. Conclusions： SMIR-induced mechanical allodynia can be partially reversed by the NF-kB inhibitor. Our results suggest that NF-r.B activation in spinal cord plays a role in SMIR-induced mechanical allodyuia in rats. Therefore, NF-kB inhibition may be useful but not sufficient for the therapeutic control of postoperative pain,     

Immune therapy with cultured microglia grafting into the injured spinal cord promoting the recovery of rat's hind limb motor function

Objective: To study the effect of activated microglia grafting on rats' hind limb motor function recovery after spinal cord injury.Methods: Microglia were separated from primary culture and subcultured for 3 generations. Lipopolysaccharide was added to the culture medium with the terminal concentrition of 10 μl/L for microglia activation 3 days before transplantation. Totally 80 adult Wistar rats were divided into transplantation group and control group, with 40 rats in each group. Spinal cord injury model of rats was set by hitting onto the spinal cord using a modified Allen impactor. With a 5 μl micro-syringe, the activated microglia suspension was injected into the injured area 7 days after the first operation. Basso, Beattie and Bresnahan (BBB) scoring for hind limb motor function was taken on the 1st, 7th, 14th, 21st, and 28th day after microglia transplantation, and 8 rats were sacrificed at each time point mentioned above, respectively. Frozen sections of the spinal cord were made for haematoxylin-eosin (HE) and Naoumenko-Feigin stainings. SPSS 11.0 software was used for statistical analysis.Results: BBB scores for hind limb motor function on the 14th, 21 st, and 28th day were significantly higher compared with the control group. Most liquefaction necrosis areas disappeared and only a few multicystic cavities surrounded by aggregated microglia remained in the transplantation group. Naoumenko-Feigin staining for microglia showed that the transplantation group had significantly more positive cells (P＜0.05).Conclusions: Grafting of activated microglia into the injured spinal cord can significantly promote the hind limb motor function recovery in rats with spinal cord injury and reduce the size of liquefaction necrosis area. The extent of lower limb motor function improvement has a positive correlation with the number of aggregated microglia.