高压氧预处理对异氟醚所致中年小鼠认知障碍的改善作用及海马脑源性神经营养因子和胶质细胞源性神经营养因子表达水平的影响

Effects of hyperbaric oxygen preconditioning on cognitive behavior and the expression of BDNF and GDNF in the hippocampus of isoflurane-induced cognitive impairment in middle aged mice

目的探讨高压氧预处理对异氟醚(ISO)所致中年小鼠认知障碍的改善作用及海马脑源性神经营养因子(BDNF)和胶质细胞源性神经营养因子(GDNF)蛋白表达和mRNA水平的影响。方法将32只8月龄雄性C57BL/6J小鼠按随机数字表随机分为对照组(sham组)、高压氧组(HBO组)、异氟醚组(ISO组)和高压氧预处理+异氟醚组(HBO+ISO组),每组8只。HBO组和ESPS+HBO组小鼠置于高压氧舱进行1 h高压氧(2.5个大气压,100%O2)干预,对照组小鼠常压空气干预(模拟除压力和氧浓度以外的其他过程和环境条件)1 h,均连续5 d。在第3天HBO或常压空气干预结束后2 h,各组小鼠进行水迷宫训练,连续3 d。最后1次水迷宫训练后24 h,ISO组和HBO+ISO组小鼠经异氟醚吸入麻醉构建认知障碍模型,其他2组吸入对照气体。24 h后进行水迷宫检测认知功能,并通过蛋白免疫印迹(Western Blot)和实时定量聚合酶链式反应(RT-PCR)检测小鼠海马BDNF和GDNF蛋白表达和mRNA水平的变化。结果(1)各处理组水迷宫总运动距离和平均运动速度的差异均无统计学意义(均P>0.05);ISO组目标象限停留时间百分比为(26.74±10.52)%,显著低于sham组[(48.33±9.18)%,P<0.01],而HBO+ISO组[(39.06±8.39)%]则显著高于ISO组(P<0.05)。(2)ISO组海马BDNF(0.56±0.09)和GDNF(0.52±0.10)的蛋白相对表达水平均显著低于sham组和HBO+ISO组(均P<0.01或0.05)。(3)ISO组海马BDNF(0.51±0.08)和GDNF(0.25±0.09)的mRNA相对水平也均显著低于sham组和HBO+ISO组(均P<0.01)。(4)sham组与HBO组在上述行为和分子水平之间的差异均无统计学意义(均P>0.05)。结论高压氧预处理可能通过调节海马的BDNF和GDNF表达水平,改善异氟醚所致认知损伤。

Objective To investigate the effect of hyperbaric oxygen(HBO)preconditioning on isoflurane(ISO)-induced cognitive impairment in middle-aged mice,and the effects of hyperbaric oxygen(HBO)pretreatment on the protein expression and mRNA levels of brain-derived neurotrophic factor(BDNF)and glial cell-derived neurotrophic factor(GDNF)in hippocampus.Methods A total of 32 male 8-month-old C57BL/6J mice were randomly divided into four groups by random number table with 8 in each group:sham group,HBO group,ISO group and HBO+ISO group.Mice in HBO group and ESPs+HBO group were put into hyperbaric oxygen chamber for 1 h(2.5 atmospheres,100%O2),while those in control group were intervened by atmospheric pressure(simulating other processes and environmental conditions except pressure and oxygen concentration)for 1 h,which lasted for 5 days.On the third day after HBO or atmospheric air intervention,mice in each group were given water maze training for 3 days.24 hours after the last water maze training,the cognitive impairment models were established by isoflurane inhalation anesthesia in ISO group and HBO+ISO group,while the other two groups inhaled control gas.After 24 hours,the cognitive function was detected by water maze,and the protein expression and mRNA levels of BDNF and GDNF in hippocampus of mice were detected by Western blot and real-time quantitative polymerase chain reaction(qPCR).Results(1)There was no significant difference in the total movement distance and average movement speed in water maze test among each group(P>0.05);the relative time dwell time in target quatrant in the ISO group was(26.74±10.52)%,which was significantly lower than that in the sham group(48.33.74±9.21)%(P<0.01),while that in HBO+ISO group(39.06±8.38)%was significantly higher than that in ISO group(P<0.05).(2)The relative expression levels of BDNF(0.56±0.09)and GDNF(0.52±0.10)in hippocampus of ISO group were significantly lower than those in sham group and HBO+ISO group(P<0.01 or 0.05).(3)The relative mRNA levels of BDNF(0.51±0.08)and GDNF(0.25±0.09)in hippocampus of ISO group were also significantly lower than those in sham group and HBO+ISO group(P<0.01).(4)There was no significant difference between sham group and HBO group in the above parameters(P>0.05).Conclusions Hyperbaric oxygen preconditioning may improve isoflurane induced cognitive impairment by regulating the expression of BDNF and GDNF in hippocampus.