果糖饮水对小鼠代谢和学习记忆影响的性别差异研究

Gender differences of effects of fructose drinking water on metabolism,learning and memory in mice

目的:探讨果糖饮水对小鼠代谢和学习记忆影响的性别差异及产生差异的可能机制。方法:选取6~8周龄C57BL/6N雌、雄小鼠适应性饲养1周,按性别随机分为4组,每组6只,分别为雄性对照组、雄性果糖组、雌性对照组和雌性果糖组,其中对照组小鼠给予标准饲料加普通饮用水,果糖组给予标准饲料加30%果糖饮用水,每周记录小鼠体重。持续喂养11周后用Morris水迷宫实验测试小鼠空间记忆能力。喂养12周处死小鼠,取动物血清、肝脏和内脏脂肪;检测血清天门冬氨酸氨基转移酶(AST)、丙氨酸氨基转移酶(ALT)、总胆固醇(TC)、甘油三酯(TG)、高密度脂蛋白胆固醇(HDL-C)、低密度脂蛋白胆固醇(LDL-C)水平;肝组织行苏木精—伊红(HE)染色、油红O染色,观察肝脏组织病理学变化;RT-qPCR检测肝脏ChREBP、SREBP-1c、ACC1、CPT-1、FGF21基因表达。结果:喂养12周后,雌性果糖组体重、肝重及内脏脂肪重量显著高于雌性对照组(P<0.05),而雄鼠体重、肝重及内脏脂肪重量不受果糖影响;与对照组比较,雌、雄果糖组空腹血糖均升高(P<0.05),雌性果糖组较雄性果糖组增加更为显著;与相应对照组相比,雌、雄果糖组血清AST、ALT水平未发生改变(P>0.05),雌性果糖组血清TC、HDL-C、LDL-C水平显著升高(P<0.05),雄性果糖组血清TG、LDL-C水平显著升高(P<0.01);肝组织病理结果显示,与相应对照组相比,雌性果糖组小鼠的肝脏出现了明显的脂质沉积、炎症细胞浸润等改变;水迷宫结果显示,与相应对照组相比,雌性果糖组在第4天和第5天的逃避潜伏期显著延长(P<0.05),第6天穿越平台次数及在目标象限停留时间显著减少(P<0.05);雄性果糖组未发生显著变化(P>0.05);与相应对照组相比,小鼠的平均泳速没有显著变化(P>0.05);脂肪生成基因ChREBP、SREBP-1c、ACC1表达在雌、雄小鼠中没有变化(P>0.05);脂肪酸氧化关键基因CPT-1仅在雌鼠中表达降低(P<0.01);影响食欲的因子FGF21在雄鼠中表达增加(P<0.01)。结论:30%果糖饮水对C57BL/6N小鼠代谢及学习记忆的影响存在着性别差异,果糖饮水更易诱导雌性小鼠出现糖脂代谢紊乱及学习记忆能力降低,造成这种性别差异的原因可能是雌、雄小鼠对果糖的偏好不同。

Objective:To explore the gender differences and possible mechanisms of the effects of fructose drinking water on metabolism,learning and memory in mice.Methods:C57BL/6N male and female mice aged 6 to 8 weeks were bred for 1 week and were randomly divided respectively into 4 groups according to gender with 6 animals in each group.male control group,male fructose group,female control group and female fructose group.The mice in the control group were given standard diet plus ordinary drinking water,and the mice in the fructose group were given standard diet plus 30%fructose drinking water,with body weight recorded weekly.Morris water maze test was used to test the spatial memory ability of mice after continuous feeding for 11 weeks.The mice were sacrificed after 12 weeks of feeding,and the serum,liver and visceral fat of the animals were collected.The levels of serum aspartate aminotransferase(AST),alanine aminotransferase(ALT),total cholesterol(TC),triglyceride(TG),high density lipoprotein cholesterol(HDL-C)and low density lipoprotein cholesterol(LDL-C)were detected.Liver tissues were stained with HE and oil red O to observe histopatho-logical changes of liver.The expressions of ChREBP,SREBP-1c,ACC1,CPT-1 and FGF21 in liver were detected by real-time fluorescence quantitative polymerase chain reaction(RT-qPCR).Results:After 12 weeks of feeding,the body weight,liver weight and visceral fat weight of female fructose group were significantly higher than those of female control group(P<0.05),while the body weight,liver weight and visceral fat weight of male rats were not affected by fructose.Compared with the control group,the fasting blood glucose in both male and female fructose groups increased(P<0.05),and the female fructose group increased more significantly than the male fructose group.Compared with their control groups,serum AST and ALT were not changed in male and female fructose groups(P>0.05);the serum levels of TC,HDL-C and LDL-C in female fructose group significantly increased(P<0.05),and the serum levels of TG and LDL-C in male fructose group significantly increased(P<0.01).Liver histopathological results showed that the liver of the female fructose group mice showed obvious changes in lipid deposition and inflammatory cell infiltration compared with their control groups.The results of water maze showed that compared with their control groups,the escape latency of female fructose group was significantly prolonged on the 4th and 5th day(P<0.05),and the times of crossing the platform and staying time in the target quadrant were significantly reduced on the 6th day(P<0.05).There were no significant changes in male fructose group(P>0.05).Compared with their control groups,there were no obvious changes in the average swimming speed of mice(P>0.05)and no changes in the expressions of adipogenic genes ChREBP,SREBP-1c and ACC1 in male and female mice(P>0.05);the expression of CPT-1,a key gene of fatty acid oxidation,decreased only in female mice(P<0.01)and the expression of FGF21,a factor affecting appetite,increased in male mice(P<0.01).Conclusion:There are gender differences in the effects of 30%fructose drinking water on metabolism and learning and memory of C57BL/6N mice.Fructose drinking water is more likely to induce disorder of glucose and lipid metabolism and decrease learning and memory ability in female mice.The reason for the gender differences may be that male and female mice have different preferences for fructose.