腹腔注射氯胺酮对胫骨癌痛模型大鼠腰段脊髓磷酸化胞外信号调节蛋白激酶表达的影响

Effects of intraperitoneal ketamine on phosphorylation of extracellular signal-regulated kinase in lumbar spinal cord neurons induced by tibial cancer pain in rats

目的观察腹腔注射氯胺酮对骨癌痛模型大鼠患侧腰段脊髓背角磷酸化胞外信号调节蛋白激酶(pERK)表达的影响,探讨氯胺酮治疗骨癌痛的可能机制。方法选择成年雌性SD大鼠24只,体重180～220g,随机分为4组(n=6):A组(对照组):左侧胫骨上段骨髓腔注入3μLHank液;B组(模型组):左侧胫骨上段骨髓腔注入3μLMADB-106大鼠乳腺癌细胞(4.8×109/L);C组(氯胺酮10mg/kg);D组(氯胺酮20mg/kg);C,D二组造模同B组。从第14d开始,A,B组大鼠腹腔分别注射生理盐水1mL,C,D组大鼠腹腔分别注射氯胺酮10mg/kg(1mL)及20mg/kg(1mL),1次/d,连续4d。术前及术后1～22d,各组大鼠隔日观察机械痛阈值变化。第22天,取大鼠脊髓L4～6节段,采用免疫组织化学方法观察脊髓背角pERK的表达。结果A组大鼠对机械刺激的缩爪阈值在术后各时间点组内相比差异无统计学意义;术后14～22d,与A组大鼠对机械痛刺激缩爪阈值相比,B、C组差异有统计学意义(P<0.05)而D组差异无统计学意义(P>0.05)。大鼠腰脊髓背角Ⅰ～ⅣpERK免疫反应光密度值B、C组与A组相比差异有统计学意义(P<0.05),D组与A组相比差异无统计学意义。结论腹腔注射20mg/kg氯胺酮抑制了胫骨癌痛模型大鼠患侧腰段脊髓背角pERK表达,NMDA/ERK信号通路的激活参与了骨癌痛的维持。

[Objective] To investigate the effects of repeated intraperitoneal administration of ketamine on phosphorylation of extracellular signal-regulated kinase in the lumbar spinal cord neurons induced by the tibial cancer pain in rats. [Methods] Twenty-four SD female rats weighing 180-220 g were randomly divided into 4 groups （n=6 each）： A group （control group）： intra-tibial injection of 3 p.L Hank＇s solution; B group （model group）： intra-tibial injection of 3 p.L MADB-106 mammary gland carcinoma cells of rats （4.8×10^9 cells/μL）; C group （ketamine 10 mg/kg group）; D group （ketamine 20 mg/kg group）. The procedures in C and D group were the same as those in the B group. From the 14th day of operation, 10 mg/kg ketamine （1 mL） and 20 mg/kg ketamine （1 mL） were injected intraperitoneally into C and D group respectively and normal saline lmL was injected into A and B group per day for 4 days. Mechanical withdrawal thresholds of rats＇ hind paws were measured every other day from one day before operation until 22 days later. The lumbar 4-6 spinal cord was removed on the 22nd day. The changes of the spinal pERK immunoreactivity were detected by immunohistochemistry SABC method. [Results] No significant differences in mechanical withdrawal threshold were found at all time points in A group. During 14-22 day after operation, mechanical pain thresholds in B and C group were significantly different from those of A group （P 〈0.05）, but the differences were not remarkable between A and D group, The pERK immunoreactivity of B and C group in laminae Ⅰ - Ⅳ of dorsal horn showed stronger staining than A group （P 〈0.05）. No significant difference of pERK immunoreactivity was found between D group and A group （P 〉0.05）. [Conclusion] Our results show intraperitoneal ketamine provides analgesia in the tibial cancer pain rats and inhibits phosphor）clarion of extracellular signal-regulated kinase in the lumbar spinal dorsal horn neurons, suggesting that activation of NMDA/ERK signal pathway is involved in the bone cancer pain.