低浓度异氟烷麻醉对不同鼠龄小鼠认知功能损害程度比较

Comparison of the change in learning and memory function between different age mice after low-concentration isoflurane anesthesia

目的比较低浓度异氟烷对不同鼠龄小鼠记忆及学习功能影响的差异。方法本研究采用低浓度异氟烷麻醉模型,以3~5月龄(成年组)及18~20月龄(老龄组)的C57/BL6小鼠为实验对象,每组20只,给予最小肺泡浓度(MAC)异氟烷(1.33%)麻醉1 h,分别于麻醉前及异氟烷麻醉后1和24 h对小鼠进行场景恐惧实验,记录小鼠相对凝滞时间。分别计算成年及老龄小鼠麻醉前与麻醉后1 h凝滞时间变化率,以及其麻醉后1和24 h的凝滞时间变化率。结果凝滞时间测试结果显示,未麻醉成年组小鼠为(135.1±31.5)s、老龄组为(188.9±13.0)s;低浓度异氟烷麻醉后1 h、24 h成年组小鼠凝滞时间分别为(61.3±10.7)和(87.8±9.0)s,老龄组小鼠分别为(81.8±17.6)和(75.6±13.0)s,不同鼠龄小鼠麻醉后凝滞时间均较麻醉前明显下降(均P<0.05);低浓度异氟烷麻醉前与麻醉后1 h,成年组小鼠凝滞时间变化率为(54±8.8)%,老龄组为(69±10.2)%,较成年组明显升高(P<0.05);麻醉后1和24 h成年小鼠凝滞时间变化率为(42±9.1)%,老龄小鼠凝滞时间变化率为(25±9.4)%,较成年组明显降低(P<0.05)。结论低浓度异氟烷麻醉后成年及老龄小鼠学习与记忆能力下降,其对老龄小鼠学习与记忆能力影响程度大且恢复更难。

Objective To compare the effect of low-concentration isoflurane anesthesia on the memory and learning function in young and older mice. Methods The 3-5 month old(adult group)and 18-20 month old(aged group)C57/BL6 mice were used to perform the low-concentration isoflurane anesthesia. Twenty mice in each group were given minimum alveolar concentration(MAC)isoflurane(1.33%)for 1 h. All rats were subjected to fear conditioning test before and 1 h and 24 h after isoflurane anesthesia,and the stagnation time(t)of the mice was recorded. The rate of change of stagnation time(△t1)before and after anesthesia in the two groups was calculated,and the rate of change in stagnation time(△t24)between 1 h and 24 h after anesthesia was calculated for each group.Results The stagnation time before anesthesia for the adult and aged groups was(135.1 ±31.5)and(188.9 ±13.0)s,respectively.The stagnation time for 1 and 24 hours after anesthesia was(61.3 ±10.7)and(87.8 ±9.0)s in the adult group and(81.8 ±17.6)and(75.6 ±13.0)s in the aged group,respectively. The stagnation time after anesthesia was significantly shortened in both the adult and aged groups(all P<0.05). The change rate of stagnation time between before and 1 h after anesthesia was(54 ±8.8)% in adult group and(69 ±10.2)% in aged group,and the change rate was significantly higher in aged group than in adult group(P<0.05). The change rate of stagnation time between 1 and 24 hours after anesthesia was(42 ±9.1)% in adult group and(25 ±9.4)% in aged group,and the change rate was significantly lower in aged group than in adult group(P<0.05). Conclusion The learning and memory ability was declined both in adult and aged mice after low-concentration isoflurane anesthesia. The influence of the low-concentration isofurane anesthesia on the learning and memory ability was more serious in aged mice than in adult mice,which makes it more difficult for the aged mice to recover.