| Objective To investigate the expression of NR2B on the dorsal horn of murine spinal cord in chronic inflammation pain, neuropathic pain and cancer pain model ,try to approach the effects of NR2B in different kinds of chronic pain.Method Thirty five male C57BL/6 mice (18-20g) were randomly divided into seven group: Normal control group(C group 5 mice), no treatment given. Chronic inflammatory pain group(Fl group 5 mice): 20μl Freund's adjuvant were injected subcutaneouly in sole of the left foot. Inflammatory pain control group(F2 group 5 mice): 20μl physiological saline were injected subcutaneously in sole of the left foot. Neuropathic pain group(Nl group 5 mice): the left sciatic nerve was exposed, and then ligated lightly four times. Neuropathic pain control group(N2 group 5 mice): the left sciatic nerve was exposed, but didn't ligate. Bone cancer pain group(T1 group 5 mice): 2×10~6 cell in 10μl PBS were injected into murine left femur. Bone cancer pain control group(T2 group 5 mice): PBS 10μl was injected into murine left femur. 7 days after operation, Spontaneous lifting time and mechanical allodynia threshold of mice hind paw were measured in alternative days. 15 days after operation, segments of lumbar spinal cord were taken to detect NR2B by immunohistochemistry, the left femur in mice of bone cancer pain group was stained with HE.Result 1) 7 days after operation, all model groups displayed spontaneous pain, and the course of flinch lasted more time in later experimental session; the bone cancer pain group displayed the gradual development of mechanical allodynia, the 50% von Frey threshold significantly decreased on day 11 after injection and lasted the whole experimental period; chronic inflammatory pain group and neuropathic pain group displayed mechanical allodynia on day 7 after operation(the first day of observation period) and lasted the whole experimental period; Meanwhile, we can see plenty of tumor cells in the medullary canal of bone cancer pain group. These models were successful established and confirmed by all of ethology and histology. 2) The immunohistochemistry result of NR2B in spinal cord: The actual staining gray scale were 58.92±4.61 in the chronic inflammatory pain group, there were significant differences in the actual staining gray scale between chronic inflammatory pain group and control group, also between chronic inflammatory pain group and normal group (P<0.05). The actual staining gray scale were 75.44±5.32 in the neuropathic pain group, there were significant differences in the actual staining gray scale between neuropathic pain group and control group, also between neuropathic pain group and normal group (P<0.05). The actual staining gray scale were 73.00±6.07 in the bone cancer pain group, there were significant differences in the actual staining gray scale between bone cancer pain group and control group, also between bone cancer pain group and normal group (P<0.05). Three pain model groups compared each other, there were differences between chronic inflammatory pain model group and neuropathic pain group (P<0.05), also between chronic inflammatory pain model group and bone cancer pain group (P<0.05). but there was no differences between neuropathic pain group and bone cancer pain group(P>0.05). moreover there was no differences between control group and normal group(P>0.05).Conclusion In C57BL/6 mice, three pain models could display spontaneous pain and mechanical allodynia, furthermore the expression of NR2B was increased in bone cancer pain, neuropathic pain and chronic inflammatory pain model on the dorsal horn of murine spinal cord, bone cancer pain and neuropathic pain were higher than chronic inflammatory pain. so the NR2B in spinal cord may participate and mediate in algesthesia maintenance in chronic pain, but the effects of NR2B weren't identical in different kinds of chronic pain. |
