不同剂量异氟醚对中年小鼠认知功能及海马MBP和pNF-H表达的影响

Effect of Isoflurane on the Cognitive Function and Expression of Myelin basic Protein (MBP) and Phosphorylated Neurofilament Heavy Polypeptide (pNF-H) in the Hippocampus of Middle-aged Mice

目的:探讨异氟醚对中年小鼠认知功能及海马髓磷脂碱性蛋白(MBP, myelin basic protein)和磷酸化神经丝重亚单位(pNF-H,phosphorylated neurofilament heavy chain)表达的影响。方法:给予中年小鼠不同浓度的异氟醚处理,实验分为对照组和异氟醚处理组(0.5ISO,1.0ISO,1.5ISO),其中异氟醚组小鼠细胞分别给予0.5 MAC,1.0 MAC和1.5 MAC三个浓度的异氟醚处理4小时,对照组给予O_2处理4小时,随后通过水迷宫测试检测其学习记忆能力变化,通过免疫荧光检测海马形态结构及髓鞘相关蛋白MBP和pNF-H表达变化。结果:与对照组相比,(1)类临床浓度的异氟醚处理不影响中年小鼠的自发运动能力(总运动距离:sham:7275.17±1732.58; 0.5ISO:8057.58±1732.58; 1.0ISO:7540.98±1401.61; 1.5ISO:8243.79±1257.65;运动速度:sham:116.75±22.35; 0.5ISO:135.45±32.84; 1.0ISO:130.16±21.38; 1.5ISO:142.31±20.58),但1.0 MAC和1.5 MAC的异氟醚处理明显降低了中年小鼠在水迷宫目标象限的活动时间百分比(sham:58.62±13.70; 0.5ISO:48.92±7.22; 1.0ISO:31.23±13.16; 1.5ISO:30.29±15.76)(P <0.05),且高浓度异氟醚作用强于低浓度异氟醚;(2) 1.0 MAC和1.5 MAC的异氟醚处理明显下调了海马的MBP和p NF-H表达(MBP:sham:60.48±8.20; 0.5ISO:56.69±7.86; 1.0ISO:40.15±4.50; 1.5ISO:31.66±5.46; pNF-H:sham:62.23±9.45; 0.5ISO:55.47±6.98; 1.0ISO:40.16±6.97; 1.5ISO:30.94±5.89)(P <0.05),造成了小鼠海马髓鞘结构损伤,且高浓度损伤强于低浓度。结论:异氟醚可能通过下调中年小鼠海马MBP和pNF-H表达,破坏海马髓鞘完整性而损伤小鼠的学习认知能力。

Objective: To investigate the effect of isoflurane(ISO) on the cognitive function and the expression of myelin basic protein(MBP)and phosphorylated neurofilament heavy polypeptide(pNF-H) in the hippocampus of Middle-aged mice. Methods:Twenty-four 8-month-old mice were divided into control and isoflurane groups(0.5ISO, 1.0ISO and 1.5ISO): control group was treated with O2 for 4 hours and isoflurane treatment groups(0.5ISO, 1.0ISO and 1.5ISO) were treated with 0.5 MAC, 1.0 MAC and 1.5 MAC of isoflurane for 4 hours respectively(n = 6 for each group). After 24 hours of isoflurane treatment, cognitive function was determined by Morris Water Maze(MWM) test, and then mice were perfused and the expression of MBP and pNF-H in the hippocampus were detected by immumofluorescence method. Results: Compared with the control(sham: 0.53 ±0.14),(1) 1.0 MAC(0.31 ±0.13) and 1.5 MAC(0.30 ± 0.16) isoflurane treatment significantly decreased the time spent in target quadrant with the platform of hippocampus of Middle-aged mice(P<0.05);(2) 1.0 MAC and 1.5 MAC isoflurane treatment significantly decreased the expression of MBP( sham: 60.48±8.20;0.5 ISO: 56.69 ±7.86;1.0 ISO: 40.15 ±4.50;1.5 ISO: 31.66 ±5.46) and pNF-H(sham: 62.23 ±9.45;0.5 ISO: 55.47 ±6.98;1.0 ISO: 40.16 ±6.97;1.5 ISO: 30.94 ±5.89) in hippocampus of Middle-aged mice(P<0.05). Conclusion: Isoflurane exposure disturbed the expression of MBP and pNF-H in the hippocampus and induced memory impairment in middle-aged mice.