七氟烷暴露频次对大鼠发育脑神经毒性及对神经发育影响的研究

Effects of the frequency of exposure to sevoflurane on developmental brain neurotoxicity and neurodevelopment in rats

目的探讨麻醉药物七氟烷暴露频次与大鼠发育脑神经毒性的关系及对神经发育的影响。方法将出生7 d的76只SD大鼠按照随机数字表法分为对照组、单次七氟烷暴露组(S 1组)、连续2 d七氟烷暴露组(S 2组)、连续3 d七氟烷暴露组(S 3组),每组各19只。将SD大鼠接受2%七氟烷+50%O 2暴露,暴露时间为4 h。记录各组大鼠pH值、氧分压、二氧化碳分压和血氧饱和度。通过末端脱氧核苷酸转移酶dUTP末端标记(TUNEL)染色评估大鼠大脑皮层和海马区的神经元凋亡情况,并通过Morris水迷宫实验探索大鼠空间学习和记忆能力。结果各组大鼠血气分析结果比较,差异均无统计学意义(P>0.05)。S 3组大鼠皮层中的神经元凋亡细胞数量显著高于对照组[(54.17±13.89)个vs.(5.67±3.08)个],S 3组大鼠海马中的神经元凋亡细胞数量显著高于对照组[(25.50±8.46)个vs.(6.17±1.94)个],差异均有统计学意义(P<0.05)。而S 1、S 2组皮层区和海马区神经细胞凋亡数量与对照组比较,差异均无统计学意义(P>0.05)。S 3组大鼠在Morris水迷宫实验第3天寻找隐藏平台的时间显著长于对照组[(23.79±10.60)s vs.(13.04±8.83)s],第6天在目标象限中的游泳时间百分比显著低于对照组[(30.79±4.55)%vs.(40.42±9.92)%],差异均有统计学意义(P<0.05)。而S 1组和S 2组大鼠在Morris水迷宫实验第3天寻找隐藏平台的时间、第6天撤去平台后在目标象限所占时间百分比与对照组比较,差异均无统计学意义(P>0.05)。S 3组大鼠Morris水迷宫实验第6天在泳池中的游泳轨迹与S 1组和S 2组不同,呈现随机游泳轨迹。结论连续3 d七氟烷暴露与发育脑的神经毒性有关,并导致随后神经发育缺陷。同时本研究为进一步探索全身麻醉药对发育脑的影响提供了简单实用的动物模型。

Objective To investigate the ralationshi betueen the frequency of exposure to sevoflurane and neurotoxicity and its effect on neurodevelopmental in rats.Methods Seventy-six SD rats 7 days after birth were divided into four groups according to the random number table method:control group,single exposure to sevoflurane for a single day(S 1 group),exposure to sevoflurane for two consecutive days(S 2 group),exposure to sevoflurane for three consecutive days(S 3 group),each group 19 rats.SD rats were exposed to 2%sevoflurane+50%O 2 for 4 hours.The pH value,oxygen partial pressure,carbon dioxide partial pressure,and blood oxygen saturation of each group of rats were recorded.Terminal deoxynucleotidyl transferase dUTP nick end labeling(TUNEL)staining was used to evaluate neuronal apoptosis in the cerebral cortex and hippocampal region.And the cognitive function of rats was explored by Morris water maze test.Results There was no statistically significant increase in the blood gas analysis results among different groups of rats(P>0.05).The number of apoptotic neurons in the cortex of S 3 group rats was significantly higher than that in the control group(54.17±13.89 vs.5.67±3.08),the number of apoptotic neurons in the hippocampus of S 3 group rats was significantly higher than that in the control group(25.50±8.46 vs.6.17±1.94),the differences were statistically significant(P<0.05).However,there was no statistically significant difference in the number of apoptotic neurons in the cortex and hippocampus of the S 1 and S 2 groups compared to the control group(P>0.05).The time to search for hidden platforms on the 3rd day of Morris water maze test of S 3 group rats was significantly longer than that of the control group[(23.79±10.60)s vs.(13.04±8.83)s],and the percentage of swimming time in the target quadrant on the 6th day was significantly lower than that of the control group[(30.79±4.55)%vs.(40.42±9.92)%],the differences were statistically significant(P<0.05).However,there was no statistically significant difference between the S 1 and S 2 groups of rats in the time to search for hidden platforms on the 3rd day of Morris water maze test and the percentage of swimming time in the target quadrant on the 6th day compared to the control group(P>0.05).In addition,swim patterns showed that rats in S 3 group swam in random circles throughout the pool on the 6th day of Morris water maze test,which was different from other groups.Conclusion Multiple sevoflurane exposure for three consecutive days is associated with the neurotoxicity in the developing brain and lead to the subsequent neurodevelopmental defects in later life.The present study also provides an effective animal model for further studies exploring the effects of general anesthetics on developing brain.