有氧运动调节AD模型小鼠海马乳酸代谢的适应性变化

Adaptive Changes in Hippocampal Lactate Metabolism in AD Model Mice Regulated by Aerobic Exercise

目的:探讨有氧运动对AD模型临床早期脑乳酸水平及其产生与穿梭过程的影响。方法:SPF级4月龄C57BL/6J小鼠和APP/PS1/tau三转基因AD模型小鼠随机分为:正常安静组(CS,n=20)和运动组(CE,n=20),AD安静组(AS,n=20)和运动组(AE,n=20)。CE和AE组进行8周跑台运动,运动强度为50%~60%VO.2max:前10 min运动负荷12 m/min,后50 min运动负荷15 m/min,每周5 d。运动干预后即刻取尾尖血,48 h后取脑脊液及海马组织,测定乳酸浓度;免疫荧光染色观察星形胶质细胞形态;蛋白质免疫印迹法检测有氧糖酵解相关酶及乳酸转运体蛋白表达水平;采用双因素方差分析进行数据分析。结果:1)运动后即刻血乳酸在CE和AE组中出现下降趋势,AE组降低显著(P<0.05)。与CS相比,AS组脑脊液乳酸含量无明显变化,但其海马组织乳酸浓度明显降低;AE组较AS组脑脊液及海马组织乳酸浓度明显升高(P<0.05);CE组仅脑脊液乳酸浓度较CS组明显升高(P<0.05)。2)与CS组相比,AS组和CE组星形胶质细胞分支增加。3)糖酵解关键酶HXK1、HXK2、PKM2在AS组显著降低,运动干预后AE组HXK1和PKM2表达明显升高(P<0.05),CE组与CS组相比无显著变化。4)乳酸转运蛋白MCT2、MCT4和缝隙连接蛋白CX43在AS组中的表达较CS组明显降低(P<0.05),AE组MCT1、MCT4和CX43的表达较AS组明显升高(P<0.05),CE与CS组相比无明显变化。结论:有氧运动可以改善6月龄该AD模型海马有氧糖酵解代谢过程,促进脑内乳酸的产生及转运,这可能是有氧运动改善AD突触可塑性的重要机制之一。

Objective:To investigate the effect of aerobic exercise on cerebral lactate level and its production and shuttle process in the early clinical stage of AD models.Methods:4-month-old SPF grade C57BL/6J mice and APP/PS1/tau 3×Tg AD mice were randomly divided into four groups:control+sedentary group(CS,n=20)and exercise group(CE,n=20),AD+sedentary group(AS,n=20)and exercise group(AE,n=20).CE and AE groups were subjected to 8-week treadmill running with an exercise intensity of 50%to 60%V.O2max:12 m/min for 10 min,followed by 50 minutes at 15 m/min,5 days per week.Immediately after exercise intervention,tail-tip blood was taken,hippocampal tissue and cerebrospinal fluid were taken 48 h later,and lactate concentration was measured.Immunofluorescence staining was used to observe the morphology of astrocytes.Western blot was adopted to detect the protein expression of aerobic glycolysis-related enzymes and lactate transporter.Two-Way ANOVA was used for data analysis.Results:1)Blood lactate level immediately after the exercise showed a decreasing trend in both CE and AE group,and the decrease was significant in AE group(P<0.05).Compared with CS group,there was no significant change in cerebrospinal fluid lactate content in AS group,but the hippocampal lactate concentration was significantly decreased.Compared with AS group,the lactate concentration in cerebrospinal fluid and hippocampus was significantly higher than that in AE group(P<0.05).Cerebrospinal fluid lactate concentration in the CE group was significantly higher than that in CS group(P<0.05);2)Compared with CS group,the branches of astrocyte were increased in AS group and CE group;3)The expressions of HXK1,HXK2 and PKM2,which are the key enzymes in glycolysis,were significantly decreased in AS group,and the expressions of HXK1 and PKM2 were significantly increased in AE group after exercise intervention(P<0.05),while there was no significant difference between CE group and CS group;4)The expression of lactate transporter proteins MCT2,MCT4 and gap junction protein CX43 in AS group were significantly lower than those in CS group(P<0.05),the expressions of MCT1,MCT4 and CX43 in AE group were significantly higher than those in AS group(P<0.05),and there was no significant change in CE group compared with CS group.Conclusion:Aerobic exercise can improve the process of aerobic glycolytic metabolism and promote the production and transport of lactate in the hippocampus of 6-month-old 3×Tg AD mice,which may be one of the important mechanisms by which aerobic exercise to improve synaptic plasticity in AD.