不同剂量氯胺酮对骨癌大鼠痛行为学及腰段脊髓胶质细胞活化的影响

Effects of ketamine on glial activation in the lumbar spinal cord of the bone cancer pain rats

目的 观察不同剂量氯胺酮对骨癌大鼠痛行为学及腰段脊髓胶质细胞活化的影响,探讨氯胺酮治疗骨癌痛的机制.方法 将雌性SD大鼠24只,随机分为4组（n=6）：A组（对照组）：左侧胫骨上段骨髓腔注入3μl Hank液;B组（模型组）：左侧胫骨上段骨髓腔注入3μl MADB-106大鼠乳腺癌细胞（4.8×10^9/L）;C组（氯胺酮10 mg/kg）;D组（氯胺酮20 mg/kg）;C、D两组造模同B组.从第14天开始,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10 mg/kg（1 ml）及20 mg/kg（1 ml）,1次/天,连续4d.术前及术后22 d,各组大鼠隔日观察机械痛及辐射热痛阈值变化.第22天,取大鼠脊髓L4～6节段,采用免疫组织化学法观察骨癌痛大鼠腰段脊髓中星形胶质细胞胶质纤维酸性蛋白（GFAP）免疫反应阳性产物及OX42标记的小胶质细胞阳性产物分布及变化.结果 A组大鼠对机械、辐射热痛刺激的缩爪阈值在术后各时间点组内比较差异无统计学意义（P＞0.05）;B、C、D组大鼠对辐射热痛刺激缩爪阈值在术后的前6d与A组比较升高（P＜0.05）,术后14～ 22 d,与A组大鼠对机械痛刺激缩爪阈值和辐射热痛阈值比较,B、C组降低（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～ⅣGFAP、OX42免疫反应吸光度值B组（57.05＆#177;2.03、72.04 ＆#177;2.25）、C组（52.02＆#177;2.08、69.32 ＆#177;2.14）比A组（30.62＆#177;1.06、42.34 ＆#177;3.16）升高（P＜0.05）,D组与A组比较差异无统计学意义（P＞0.05）.结论 骨癌痛模型大鼠患侧腰段脊髓背角星形胶质细胞和小胶质细胞均被广泛激活,20 mg/kg氯胺酮可以显著抑制其激活.

Objective To investigate the effects of repeated administration of ketamine on glial activation in the lumbar spinal cord of the bone cancer pain rats.Methods Twenty-four SD female rats weighing 180-220 g were randomly divided into 4 groups （n =6 each）：group A （control group）,intra-tibial injection of 3 μl Hank＇ s solution; group B （model group）,intra-tibial injection of 3 μl MADB-106 mammary gland carcinoma cells of rats （4.8 × 10^9/L） ; group C （ketamine 10 mg/kg） ; group D （ketamine mg/kg）.The procedures in groups C and D were the same as those in the group B.From the 14th day of operation,ketamine （10 and 20 mg/kg,1 ml） was injected intraperitoneally into groups C and D respectively,and normal saline （1 ml） was injected into groups A and B per day for 4 days.Mechanical withdrawal thresholds and radiant heat threshold of rats＇ hind paws were measured every other day from one day before operation until 22 days later.The lumbar 4-5 spinal cord was removed on the 22nd day.The changes of the spinal glial fibrillary acidic protein （GFAP） and OX42 immunoreactivity were detected by immunohistochemistry strept avidin-biotin complex （SABC） method.Results No significant differences in mechanical withdrawal threshold and radiant heat threshold were found at all time points in group A.During the first 6 days of post-operation there were obvious differences in radiant heat stimulus between group A and the other groups （P 〈0.05）.During 14-22 days after operation,mechanical pain threshold and radiant heat threshold in groups B and C were significantly different from those in group A （P 〈 0.05）,but the differences were not remarkable between groups A and D.The GFAP and OX42 immunoreactivity in group B （57.05 ＆#177; 2.03 and 72.04 ＆#177; 2.25） and group C （52.02 ＆#177; 2.08 and 69.32 ＆#177; 2.14） in laminae Ⅰ-ⅣV of dorsal horn showed stronger staining than in group A （30.62 ＆#177; 1.06 and 42.34 ＆#177;3.16,P 〈0.05）.No significant difference in GFAP and OX42 immunoreactivity was found between groups D and A （P 〉 0.05）.Conclusion Both astrocytes and microglia were activated ipsilaterally in the spinal cord of rats with MADB-106 mammary gland carcinoma cell-injected tibiae,and ketamine 20 mg/kg can repress this activation.