异氟醚对大鼠认知功能及海马高级糖基化终末产物受体表达的影响

目的 观察异氟醚对大鼠海马高级糖基化终末产物受体(receptor for advanced glycation end products,RAGE)表达及认知功能的影响.方法 SD雄性老年大鼠(24月龄)45只,SD雄性成年大鼠(4月龄)45只,随机数字表法分为6组(n=15),老年对照组(C1组),成年对照组(C2组):吸入30%氧气的空氧混合气体对照;老年异氟醚单次吸入组(S1组),成年异氟醚单次吸入组(S2组):1.5%异氟醚单次吸入2h;老年异氟醚多次吸入组(R1组),成年异氟醚多次吸入组(R2组):1.5%异氟醚吸入3次,1次/d,2h/次.各组大鼠吸入处理后1d取8只行Morris水迷宫进行认知功能测试,其余大鼠处死取海马,RT-PCR方法测定RAGE mRNA水平,免疫组织化学方法测定RAGE蛋白表达.结果 各组大鼠吸入处理过程中生命体征平稳,血氧饱和度及心率均在正常范围.C1组穿越平台次数为(7.30±2.40)次,探索时间为(49.90±6.22)s,S1、R1组与C1组相比穿越平台的次数减少穿越平台次数分别为S1(3.90±2.42),R1(3.44±2.40),F=7.448,P<0.01],探索时间缩短探索时间分别为S1(43.33±7.08)s,R1(39.09±4.56)s,F=7.63,P<0.05],而逃避潜伏期延长(P<0.05).R2组较C2组逃逸潜伏期延长逃逸潜伏期分别为R2(14.65±3.83)s,C2(7.84±2.51)s,F=12.773,P<0.01],探索时间缩短(均P<0.01),穿越平台次数减少(P<0.01).S2组与C2组比较,空间探索时间与穿越平台次数均未见显著统计学差异(P>0.05);RAGE表达:与C1组比较S1、R1组mRNA表达水平增高mRNA表达分别为c1(0.11±0.02),S1(0.56±0.09),R1(0.73±0.14)F=169.447,P<0.01],免疫组化阳性细胞颗粒数增多(P<0.01),S1组与R1组比较蛋白表达差异无统计学意义(P>0.05);与C2组比较,S2组mRNA水平及蛋白表达未见明显差异(P>0.05),但R2组mRNA及免疫组化阳性细胞表达增高,与C2组比较差异有显著意义(均P<0.01).结论 异氟醚导致不同月龄大鼠认知功能改变,尤其对老年大鼠影响显著,可能与海马RAGE表达上调有关.

Effects of isoflurance on learning and memory function and receptor for advanced glycation end products expression of hippocampus in rats

Objective To explore the effect of isofluranee on receptor for advanced glycation end products (RAGE) expression of hippocampus and learning and memory function in rats. Methods 24-month Sprague-Dawley male rats (n=45) and 4-month Sprague-Dawley male rats (n=45) were randomly divided into six groups with 15 rats each group. Group C1 (aged control group),group C2(adult control group) breath 30% oxygen and air mixed gas; Group S1(single inhalation of isoflurane aged group),Group S2(single inhalation of isoflurane adult group)were anesthetized with 1.5% isoflurane,breath 30% oxygen and air mixed gas for 2h;Group R1(Repeated inhalation of isoflurane aged group), group R2(Repeated inhalation of isoflurane adult group) were anesthetized with 1.5% isoflurane,breath 30% oxygen and air mixed gas 2h a day for three days. Eight rats randomly selected from each group were killed and their hippocampus were immediately isolated for detection of RAGE expression by immunohistochemistry and RT-PCR after accomplished treatment 24h. The remained rats' learning and memory function were assessed using Morris water-maze test. Results The results of Morris water-maze test showed that the times of acerossing the original platform and the time consumption of staying the original platform quadrant was shorter in group S1 and group R1,but the escape latency was longer than group C1(escape latency C1 (9.42± 2.63)s,S1(13.20±3.85)s,R1(17.20±3.44)s, F=12.773, P<0.05). In the group R2,the escape latency was longer but the times of accrossing the original platform and the time consumption of staying the original plat-form quadrant was shorter than group C2 (times of accrossing the original platform C1(7.30±2.40), S1(3.90± 2.42),R1(3.44±2.40), F=7.448, P<0.01).To contrast with the group C2,there were no significant differ-enees in spatial probe test in the group S2(P>0.05). The levels of mRNA and protein of RAGE in hippocampus was significantly higher in group S1 and group R1 than group C1(RAGE mRNA expression C1(0.11±0.02),S1 (0.56±0.09), R1(0.73±0.14), F=179.447, P<0.01). To contrast with the group C2, there were no differ-ences found in the levels of mRNA and protein of RAGE in group S1(P>0.05), but it was higher in the group R2 (RAGE mRNA express C2(0.22±0.04), R2 (0.41±0.08), F=40. 209, P < 0. 01). Conclusion Isoflurane can reduce learning and memory function in both aged and adult rats, but aged rats are particularly significant im-pacted. This effect may be induced by the increase of RAGE expression in hippocampas.