脆弱拟杆菌BF839可改善Fmr1 KO小鼠在不同环境下的焦虑和多动行为

Bacteroides fragilis BF839 can improve anxiety and hyperactivity of fragile X-mental retardation gene 1 knockout mice under different environments

目的观察脆弱拟杆菌BF839能否改善脆性X智力低下基因1(Fmr1)敲除(Fmr1 KO)小鼠的焦虑和多动症状。方法将30只FVB系Fmr1 KO小鼠(3周龄)按随机数字表法分为Fmr1 KO组(n=15)和Fmr1 KO+BF839组(n=15),Fmr1 KO组小鼠每天自由饮用高压灭菌自来水,Fmr1 KO+BF839组小鼠每天自由饮用BF839菌液(10 ml/d),另有11只野生型(WT)小鼠作为对照组(WT组),每天自由饮用高压灭菌自来水。干预4周后,采用旷场实验观察小鼠行动的总路程,以及在中央和周围的停留时间;采用高架十字迷宫实验观察各组小鼠进入开放臂和封闭臂的时间和次数,观察小鼠在不同环境下的焦虑和多动行为。结果在旷场实验中,Fmr1 KO+BF839组小鼠的总路程低于Fmr1 KO组小鼠,但两组均高于WT组小鼠[(8 613.57±1 379.13)cm比(9 852.19±1 994.97)cm比(4 335.07±1 332.97)cm,均P<0.05]。Fmr1 KO+BF839组小鼠的中央停留时间高于Fmr1 KO组小鼠和WT组小鼠[30.60(22.20,38.50)s比12.60(5.60,27.10)s、7.40(5.40,14.20)s,均P<0.05],而Fmr1 KO组小鼠的中央停留时间与WT组差异无统计学意义(P=0.396)。Fmr1 KO+BF839组小鼠的周边停留时间低于Fmr1 KO组小鼠[269.20(261.30,277.60)s比292.01(285.60,293.40)s,P<0.05],而两组小鼠的周边停留时间均与WT组[279.50(263.40,288.90)s]差异无统计学意义(均P>0.05)。在高架十字迷宫实验中,Fmr1 KO+BF839组小鼠的开放臂次数比例低于Fmr1 KO组小鼠[31.03(26.47,40.00)%比48.08(42.86,55.26)%,P=0.002],而与WT组小鼠开放臂次数比例[22.00(18.00,40.00)%]差异无统计学意义(P=1.000),但Fmr1 KO组小鼠开放臂次数比例却高于WT组(P=0.001)。Fmr1 KO+BF839组小鼠的开放臂的时间比例低于Fmr1 KO组小鼠[24.24(12.16,38.82)%比48.62(34.85,70.77)%,P=0.020],与WT组[11.00(3.00,34.00)%]差异无统计学意义(P=0.953),而Fmr1 KO组小鼠的开放臂的时间比例高于WT组小鼠(P=0.001)。Fmr1 KO+BF839组小鼠的进入臂总次数与Fmr1 KO组小鼠差异无统计学意义(P=0.921),但两组均高于WT组小鼠[41.00(30.00,58.00)次、40.00(34.00,48.00)次比24.00(20.00,28.00)次,均P<0.05]。结论对Fmr1 KO组小鼠早期使用BF839干预,能恢复小鼠在安全环境下的焦虑行为,以及压力下的正常焦虑反应(抗焦虑样行为),对安全环境下的多动行为也有轻度改善作用,提示BF839有潜力治疗脆性X综合征。

Objective To investigate whether bacteroides fragilis BF839 can improve anxiety and hyperactivity symptoms of fragile X-mental retardation gene 1(Fmr1)knockout(KO)mice.Methods Thirty FVB strain Fmr1 KO mice(3 weeks old)were divided into Fmr1 KO group(n=15)and Fmr1 KO+BF839 group(n=15).the Fmr1 KO group mice freely drank autoclaved tap water everyday;the Fmr1 KO+BF839 group mice were given free drinking BF839 bacterial liquid(10 ml/d)everyday;and another 11 wild type mice served as control(WT group)were given free drinking autoclaved tap water every day.After 4 weeks of intervention,the open field test was used to observe the total distance of the mice,and the residence time in the center and around the center;the elevated plus maze test was used to observe the time and times of entering the open arm and the closed arm of the mice in each group,To observe the anxiety and hyperactivity behavior of mice in different environments.Results In the open field experiment,the total distance of Fmr1 KO+BF839 group mice was lower than that of Fmr1 KO group mice,but both groups were higher than WT group mice[(8613.57±1379.13)cm vs(9852.19±1994.97)vs(4335.07±1332.97)cm,all P<0.05].The central residence time of the Fmr1 KO+BF839 group mice was higher than that of the Fmr1 KO group mice and the WT group mice[30.60(22.20,38.50)s vs 12.60(5.60,27.10)s,7.40(5.40,14.20)s,all P<0.05],while the central residence time of the Fmr1 KO group mice was not significantly different from the WT group mice(P=0.396).The peripheral residence time of the Fmr1 KO+BF839 group mice was lower than that of the Fmr1 KO group mice[269.20(261.30,277.60)s vs 292.01(285.60,293.40)s,P<0.05].However,there was no statistically significant difference in peripheral residence time between the two groups of mice and the WT group mice[279.50(263.40,288.90)s](both P>0.05).In the elevated plus maze test,the percent of open-arm entries in Fmr1 KO+BF839 group mice was lower than that in the Fmr1 KO group mice[31.03(26.47,40.00)%vs 48.08(42.86,55.26)%,P=0.002],while there was no statistically significant difference in percent of open-arm entries between the Fmr1 KO group mice and the WT group mice[22.00(18.00,40.00)%](P=1.000),the percent of open-arm entries Fmr1 KO group mice was higher than that in the WT group mice(P=0.001).the percent of open-arm time in the Fmr1 KO+BF839 group mice was lower than that in the Fmr1 KO group mice[24.24(12.16,38.82)%vs 48.62(34.85,70.77)%,P=0.020],and there was no statistically significant difference(P=0.953)compared to the WT group mice[11.00(3.00,34.00)%],while the percent of open-arm time in the Fmr1 KO group mice was higher than that in the WT group mice(P=0.001).There was no statistically significant difference in the total arm entries between the Fmr1 KO+BF839 group mice and the Fmr1 KO group mice(P=0.921),but both groups were higher than the WT group mice[41.00(30.00,58.00)entries,40.00(34.00,48.00)entries vs 24.00(20.00,28.00)entries,both P<0.05].Conclusions Early intervention with BF839 in Fmr1 KO mice restores anxiety like behavior in a safe environment;Also restoring its normal anxiety response under stress(anxiolytic like behavior)also had a mild ameliorating effect on hyperactivity behavior in a safe environment,suggesting that BF839 has potential for treating fragile X syndrome.