三种饮用水对小鼠学习记忆及海马神经递质的影响

Effect of three kinds of drinking water on learning and memory and hippocampal neurotransmitter of mice

目的探究3种饮用水对小鼠学习记忆及海马内神经递质的影响。方法测定纯水、自来水及天然矿泉水水质参数:溶解性总固体(TDS)、总硬度、耗氧量(OC)、钠、钾、钙、镁及偏硅酸。将60只ICR小鼠随机分为3组,每组20只,雌雄各半,分别用纯水(对照组)、自来水、天然矿泉水喂养90天,采用Morris水迷宫实验、避暗实验检测小鼠的学习和记忆能力,实验结束后立即处死小鼠,取海马测定乙酰胆碱(Ach)、一氧化氮(NO)、谷氨酸(Glu)、γ-氨基丁酸(GABA)含量和乙酰胆碱酯酶(ACh E)、乙酰胆碱转移酶(Ch AT)、总一氧化氮合酶(T-NOS)活性。结果自来水、天然矿泉水各水质参数均高于纯水。定位航行实验第1天,自来水组小鼠逃避潜伏期[(69.15±50.87)s]明显短于纯水组[(86.07±44.03)s],差异有统计学意义(P<0.05);与纯水组(30.00%)比较,自来水组小鼠多采用有效搜索策略(51.25%),较少采用无效搜索策略,差异有统计学意义(P<0.05)。空间探索实验中,自来水组、天然矿泉水组小鼠平台象限活动时间[分别为(28.44±10.17)s和(28.81±12.43)s]明显长于纯水组[(19.84±9.59)s],差异有统计学意义(P<0.05)。避暗实验中,自来水组、天然矿泉水组小鼠训练潜伏期[分别为(60.27±57.84)s和(58.12±42.52)s]和测验潜伏期[分别为(209.54±121.41)s和(271.40±90.44)s]均明显长于纯水组[(10.99±9.40)s和(72.77±67.51)s],且测验中小鼠5 min内电击次数[分别为(0.90±0.88)次和(0.10±0.32)次]、错误反应动物百分率(分别为50%和20%)明显少于纯水组[(5.00±4.62)次、90%],差异均有统计学意义(P<0.05)。与纯水组[(8.53±2.12)μg/mg prot和(0.94±0.49)U/mg prot]比较,自来水组、天然矿泉水组小鼠海马中Ach含量[(11.18±3.46)μg/mg prot和(12.91±3.91)μg/mg prot]明显升高、ACh E活性[(0.41±0.21)U/mg prot和(0.54±0.28)U/mg prot]明显降低,差异均有统计学意义(P<0.05)。但各组小鼠饮水量、摄食量及海马Glu、GABA、NO、Ch AT、T-NOS差异均无统计学意义(P>0.05)。结论相比于纯水,长期饮用自来水或天然矿泉水更有利于小鼠的学习与记忆,其可能与海马乙酰胆碱水平较高有关。

Objective To explore the effect of three kinds of drinking water on learning and memory and hippocampal neurotransmitter of mice. Methods Water quality parameters,including total dissolved solid（ TDS）,total hardness,oxygen consumed（ OC）,sodium,potassium,calcium,magnesium and metasilicic acid,were measured for pure water,tap water and natural mineral water. A total of 60 ICR mice（ half male and half female） were randomly divided into three groups and fed with pure water（ control group）,tap water and mineral water for 90 days. After learning-memory abilities were detected with Morris water maze and passive avoidance test, mice were killed and hippocampi were removed immediately to measure contents of acetylcholine（ Ach）,nitric oxide（ NO）,glutamic acid（ Glu） and gamma-aminobutyric acid（ GABA） and activities of acetylcholinesterase（ ACh E）,choline acetyltransferase（ Ch AT） and total nitric oxide synthase（ T-NOS）. Results Water quality parameters were higher in tap water and natural mineral water than in pure water. On the first day of place navigation test,the escape latency of tap water group [（ 69. 15 ± 50. 87） s]was obviously shorter than that of pure water group [（ 86. 07 ± 44. 03） s]（ P〈0. 05）,and mice in tap water group chose effect strategies（ 51. 25%） more frequently compared to control mice（ 30%）（ P〈0. 05）. In the probe trial,the swimming time of the targeted quadrant was significantly longer in tap water group [（ 28. 44 ± 10. 17） s] or mineral water group [（ 28. 81 ±12. 43） s] than in pure water group [（ 19. 84 ± 9. 59） s ]（ P〈0. 05）. In passive avoidance test,the training latency and testing latency were significantly longer in tap water group [（ 60. 27 ± 57. 84） and（ 209. 54 ± 121. 41） s] or mineral water group[（ 58. 12 ± 42. 52） and（ 271. 40 ± 90. 44） s]than in pure water group [（ 10. 99 ± 9. 40）and（ 72. 77 ± 67. 51） s ]（ P〈0. 05）,as the frequency of electric shock and the percentage of animals showing errors in tap water group [（ 0. 90 ± 0. 88） times and 50%]or mineral water group [（ 0. 10 ± 0. 32） times and 20%]were obviously less than those in pure water group [（ 5. 00 ± 4. 62） times and 90% ]（ P〈0. 05）. Compared with pure water group [（ 8. 53 ± 2. 12） μg / mg prot and（ 0. 94 ± 0. 49） U / mg prot],a significant increase of Ach concentration and a significant decrease of ACh E activity were observed in tap water group [（ 11. 18 ± 3. 46） μg / mg prot and（ 0. 41 ± 0. 21） U / mg prot]or mineral water group [（ 12. 91 ± 3. 91） μg / mg prot and（ 0. 54 ± 0. 28） U / mg prot]（ P〈0. 05）.Conclusion Compared with pure water,long-term drinking tap water or mineral water is more beneficial to learning and memory of mice,and it may be associated with a higher content of hippocampal Ach.