肿瘤易化小鼠术后认知功能障碍的发生

Postoperative cognitive dysfunction is easier to develop in tumor-bearing mice

目的观察荷瘤状态对成年小鼠术后认知功能障碍(POCD)的影响。方法将2月龄成年C57BL/6J雄性小鼠(23~25 g)随机分为对照组、手术组、肿瘤组和肿瘤加手术组。肿瘤组和肿瘤加手术组小鼠于右侧腋下接种小鼠来源的MC38肿瘤细胞悬液;3周后,待肿瘤长径为0.8~1.0 cm,肿瘤加手术组和手术组小鼠于氟哌利多和芬太尼复合麻醉下行胫骨骨折内固定手术。术后第3天采用Morris水迷宫实验检测各组小鼠的空间参考记忆能力;采用Western印迹法检测海马组织内术后第7天可溶性淀粉样前体蛋白α(sAPPα)和术后48 h IL-6蛋白质表达情况;术后48 h采用RT-PCR检测海马组织内IL-6 mRNA表达情况,采用ELISA检测外周血浆中IL-6含量。结果Morris水迷宫实验显示,各组小鼠间游泳速度的差异无统计学意义(P值均>0.05);实验第3和4天定位航行实验阶段,肿瘤加手术组小鼠的逃避潜伏期显著长于对照组同时间(P值分别<0.05、0.01);实验第5天空间探索实验阶段,撤掉水下平台后,肿瘤加手术组小鼠在目标象限游泳时间显著短于对照组(P<0.05),穿越平台所在位置的次数显著少于对照组(P<0.01);手术组和肿瘤组上述指标与对照组间的差异均无统计学意义(P值均>0.05)。肿瘤加手术组小鼠海马组织内sAPPα的相对蛋白质含量显著低于对照组(P<0.05),海马组织内IL-6蛋白质水平和血浆内IL-6水平均显著高于对照组(P值分别<0.01、0.05),手术组和肿瘤组上述指标与对照组相比差异均无统计学意义(P值均>0.05)。4组小鼠间海马组织内IL-6 mRNA水平的差异均无统计学意义(P值均>0.05)。结论荷瘤小鼠更容易发生POCD,其原因可能与荷瘤状态加重手术导致的外周免疫反应和促进中枢炎性反应有关。

Objective To investigate the effect of tumor-bearing state on postoperative cognitive dysfunction(POCD)in adult mice.Methods Two-month-old C57 BL/6 J male mice,weighing 23-25 g,were randomly divided into four groups:naive group,surgery group,tumor group and tumor plus surgery group.Mice of tumor group and tumor plus surgery group were inoculated with mouse-derived MC38 cancer cell suspension in the right lower armpit.Three weeks later,when the subcutaneous tumor grew up to 0.8-1.0 cm in diameter,the tibial fracture internal fixation was performed under the anesthesia with fentanyl and droperidol in the two groups.Morris water maze test was carried out to detect the spatial reference memory of mice on the 3 rd day after surgery.Hippocampal soluble amyloid precursor proteinα(sAPPα)on day 7 postoperatively and IL-6 protein level at 48 h postoperatively were measured with Western blot.At 48 h after surgery,reverse transcription-polymerase chain reaction(RT-PCR)was used to detect the expression level of IL-6 mRNA in hippocampus,and enzyme-linked immunosorbent assay(ELISA)was used to detect the concentration of IL-6 in plasma.Results In Morris water maze,there was no significant difference in swimming speed among groups(all P>0.05).On the 3 rd and 4 th day of navigation test,the escape latency in the tumor plus surgery group was significantly longer than that in the naive group(P<0.05 or 0.01).On the 5 th day,the mice in the tumor plus surgery group spent shorter time in the target quadrant than those in the naive group(P<0.05),and the frequency of crossing platform in the tumor plus surgery group was significantly less than that in the naive group(P<0.01).However,no significant differences were found in the two indexes between surgery group and naive group,between tumor group and naive group(all P>0.05).The protein level of sAPPαin the hippocampus of in the tumor plus surgery group was significantly lower than that in the naive group(P<0.05).The protein expression of IL-6 in both the hippocampus and peripheral blood of the tumor plus surgery group were significantly higher than those of the naive group(P<0.01 or 0.05),but there was no significant difference in the above-mentioned parameters between surgery group and naive group,between tumor group and naive group(all P>0.05).There was no significant difference in hippocampal IL-6 mRNA level among groups(all P>0.05).Conclusion POCD is easier to develop in tumor-bearing mice than naive mice,which is possibly related to an exacerbated peripheral immune response and neuro-inflammation induced by tumor-bearing state.