ABSTRACT
Objective To investigate the role of spinal cord chemokine CXC ligand13(CXCL13) in the formation of rat bone cancer pain(BCP).Methods Twenty healthy female SD rats weighing 160-200 g were divided into four groups(n=5):sham operation group(S),BCP group(BP),small interference RNA(siRNA) negative control(NC-siRNA) group (NC) and CXCL13-siRNA group(CS).Normal saline was given by tibial medullary cavity injection in the S group.The tibial BCP model was established by tibial medullary cavity injection of equivalent Walker-256 breast cancer cells in the group BP,NC and CS.NC-siRNA lentivirus and CXCL13-siRNA lentivirus were injected intrathecally in the group NC and CS respectively.The mechanical pain threshold was measured on 1 d before model construction and on postoperative 7,9,14,21 d.The rats were killed after pain threshold measurement.The spinal cord and tibial tissue were taken.The co-expression of spinal CXCL13,microglia specific marker Iba-1 and neuron specific neucleoprotein NeuN was determined by using the immunofluorescence double standard staining,and expressions of CXCL13 and ionized calcium binding adaptor molecule-1 (Iba-1) protein and mRNA in spinal cord were detected by Western blot and RT-PCR;the HE staining microscopy was adopted to observe the tibial bone structure destroy situation.Results Compared with group S,the mechanical pain threshold in theBP group and NC group was decreased on 7-21 d after inoculation,CXCL13 expression in neuron was significantly increased and microglia was obviously activated,the expression of CXCL13 and Iba-1 protein and mRNA was significantly elevated (P＜0.05);compared with the NC group,the mechanical pain threshold on 9-21 d after model construction in the CS group was significantly increased,CXCL13 expression in neurons was significantly decreased,microglia activation was decreased and expression of CXCL13 and Iba-1 protein and mRNA was significantly decreased(P＜0.05);HE staining showed that the model groups appeared the tumor growth in bone marrow cavity,moreover which was eroded outwards and destroyed bone cortex,but no abnormality was found in the S group.Conclusion Spinal cord CXCL13 is involved in the BCP formation in rats by activating microglia.