鞘内注射AG-490对骨癌痛小鼠脊髓水平星形胶质细胞活化和热痛觉的影响

目的：探讨脊髓水平IL-6-酪氨酸激酶-2( Janus kinase 2，JAK2)信号通路调控星形胶质细胞活化的机制及其 对骨癌痛的影响。方法：将NCTC 2472纤维肉瘤细胞注入C3H/HeNCrlVr雄性小鼠股骨骨髓腔制作骨癌痛模型，以 不含纤维肉瘤细胞的等体积α-MEM培养基行骨髓腔内注射制作假手术模型。采用热缩足反射潜伏期(paw withdrawal latency，PWL)评估疼痛水平。取腰段脊髓组织(L3~L5水平)，分别应用Real-time RT-PCR和Western印迹检测脊髓水平 星形胶质细胞中纤维酸性蛋白(glial fibrillary acidic protein，GFAP)和JAK2 mRNA与蛋白表达变化。鞘内注射给予JAK2 拮抗剂AG-490，观察小鼠痛行为学及脊髓水平GFAP mRNA和蛋白表达的变化。结果：骨癌痛模型组小鼠术后10， 14，21 d的PWL均较假手术组显著缩短(P<0.05)；骨癌痛模型组的脊髓组织GFAP和JAK2 mRNA和蛋白表达显著增加 (P<0.05)；鞘内注射30或90 nmol AG-490可以显著缩短骨癌痛模型组小鼠PWL，同时可以抑制脊髓组织GFAP mRNA和 蛋白的表达(P<0.05)。结论：脊髓水平IL-6-JAK2信号通路可能在骨癌痛的维持中发挥重要作用；IL-6-JAK2信号转导通 路可能通过抑制星形胶质细胞的活化来发挥镇痛作用。

Intrathecal injection of AG-490 reduces bone-cancerinduced spinal cord astrocyte reaction and thermal hyperalgesia in a mouse model

Objective: To investigate the role of spinal interleukin-6-Janus kinase 2 (IL-6-JAK2) signaling transduction pathway in regulating astrocytes activation during the maintenance of bone cancer pain (BCP). Methods: NCTC 2472 fibrosarcoma cells were injected into the femur marrow cavity in C3H/ HeNCrlVr male mice to establish BCP model and they were replaced by the equal volume of α-MEM in the sham model. The paw withdrawal latency (PWL) was measured after inoculation of tumor cells. The lumbar enlargement of spinal cord (L3–L5) was isolated, and Real-time RT-PCR and Western blot were used to detect the expression of spinal glial fibrillary acidic protein (GFAP) and JAK2 mRNA and protein, respectively. The expression level of spinal GFAP mRNA indirectly reflect astrocytes activation level. Pain behaviors and spinal cord GFAP mRNA and protein expression were observed at the given time points after intrathecal administration of JAK2 antagonist AG-490. Results: The PWL at 10, 14, 21 d after operation in BCP model group were significantly shorter than that in the sham group (P<0.05); the spinal GFAP and JAK2 mRNA and protein levels were higher in the BCP model group in comparison to mice in the sham group (P<0.05); intrathecal injection of JAK2 agonist AG-490 (30 or 90 nmol) significantly alleviated PWL, and downregulated the expression of spinal GFAP mRNA and protein (P<0.05). Conclusion: The IL-6-JAK2 signaling pathway plays an important role in maintaining the BCP by regulating the expression of GFAP in the spinal cord. Intrathecal injection of AG-490 can reduce the BCP, and inhibit the activation of IL-6-JAK2 signaling pathway, which may be one of the mechanisms for spinal astrocyte activation.