罗雨, 谢春, 张华, 谭瑛, 葛启迪. 慢性氟染毒对子二代大鼠海马结构和空间学习记忆的影响[J]. 环境与职业医学, 2019, 36(8): 767-772. DOI: 10.13213/j.cnki.jeom.2019.18805
引用本文: 罗雨, 谢春, 张华, 谭瑛, 葛启迪. 慢性氟染毒对子二代大鼠海马结构和空间学习记忆的影响[J]. 环境与职业医学, 2019, 36(8): 767-772. DOI: 10.13213/j.cnki.jeom.2019.18805
LUO Yu, XIE Chun, ZHANG Hua, TAN Ying, GE Qi-di. Effects of chronic fluoride exposure on hippocampal structure and spatial learning and memory of F2 rats[J]. Journal of Environmental and Occupational Medicine, 2019, 36(8): 767-772. DOI: 10.13213/j.cnki.jeom.2019.18805
Citation: LUO Yu, XIE Chun, ZHANG Hua, TAN Ying, GE Qi-di. Effects of chronic fluoride exposure on hippocampal structure and spatial learning and memory of F2 rats[J]. Journal of Environmental and Occupational Medicine, 2019, 36(8): 767-772. DOI: 10.13213/j.cnki.jeom.2019.18805

慢性氟染毒对子二代大鼠海马结构和空间学习记忆的影响

Effects of chronic fluoride exposure on hippocampal structure and spatial learning and memory of F2 rats

  • 摘要: 背景 氟可通过饮水、空气、食物等介质进入人体,过量氟进入人体除了造成骨相损害,还可通过血脑屏障在脑组织中蓄积,造成大脑神经系统损害,引起神经元联系减少及突触功能异常,导致学习记忆能力的损伤等。

    目的 探讨慢性氟染毒致子二代大鼠海马结构变化及其对大鼠空间学习记忆能力的影响。

    方法 将16只健康清洁级SD妊娠大鼠按体重随机分为4组,每组4只,分别为对照(饮用水)组和60、120、240 mg/L氟化钠暴露组,采取自由饮水方式暴露。母鼠从妊娠第0天至子一代大鼠出生第21天(postnatal day 21,PND21)暴露;子一代大鼠延续同组浓度从PND22暴露至PND90,随机选取6只大鼠(雌:雄=2:1)合笼,持续暴露至子二代大鼠PND21;从每组中随机选取8只子二代大鼠(雌:雄=1:1),自PND22至PND60按照同组氟化钠浓度继续进行暴露。Morris水迷宫及黑白箱实验检测子二代大鼠空间学习记忆能力;子二代大鼠处死前收集24 h尿液,测定脑、尿中的氟水平。暴露结束处死后,光镜和电镜下观察海马组织病理变化。

    结果 与对照组比较,中、高暴露组子二代大鼠第8周体重较轻,各浓度氟化钠暴露组子二代大鼠脑氟和尿氟水平分别为(14.23±1.86)、(18.15±1.98)、(28.74±2.19)μg/g,(11.36±0.91)、(15.30±0.26)、(18.67±2.01)μg/L,较对照组(7.06±0.79)μg/g、(1.89±0.23)μg/L高,差异均有统计学意义(P < 0.01)。水迷宫结果显示,与对照组相比,在训练第2、3天,中氟组和高氟组子二代大鼠逃避潜伏期延长,而训练第4天,各浓度氟化钠暴露组逃避潜伏期均延长,差异均有统计学意义(P < 0.05,P < 0.01);中氟组和高氟组子二代大鼠首次达台时间延长及穿越平台次数减少(P < 0.05,P < 0.01)。黑白箱实验中,中氟组与高氟组黑箱停留时间(157.25±33.17)、(209.38±10.98)s和黑箱停留时间百分比(52.42±11.06)%、(69.79±3.67)%均高于对照组(P < 0.01),高氟组穿箱次数较对照组降低(P < 0.01)。HE染色光镜观察结果显示,各暴露组海马神经细胞出现核固缩、结构模糊、染色加深等病理改变;电镜结果显示,各暴露组海马神经细胞出现线粒体肿胀,高尔基体、内质网出现不同程度扩张。

    结论 持续氟暴露可损伤子二代大鼠海马神经元结构且降低其空间学习记忆能力。

     

    Abstract: Background Fluorine can enter human body through drinking water, air, food, and other media. Excessive fluorine not only causes bone damage, but also passes through blood-brain barrier and accumulates in brain tissues, causing nervous system injury, and consequently presenting decreased neuronal connectons, abnormal synaptc functon, and impaired spatal learning and memory, ect.

    Objective This experiment is designed to explore the effects of chronic fluoride exposure on hippocampal structure and spatal learning and memory in F2 rats.

    Methods Sixteen clean SD pregnant rats were randomly divided into four groups, with four rats in each group:control (drinking water) and 60, 120, and 240 mg/L NaF groups. The pregnant rats were treated with NaF through drinking water from gestatonal day 0 to postnatal day 21 (PND21) of F1 rats. The F1 rats were treated with corresponding concentratons from PND22 to PND90, and six F1 rats (female:male=2:1) were randomly caged and followed the same protocol untl PND21 of F2 rats. Eight F2 rats (female:male=1:1) were randomly selected from each group and treated with corresponding concentratons from PND22 to PND60. The spatal learning and memory ability of the F2 rats was tested by Morris water maze and light-dark box experiment. The levels of fluorine in the F2 rat brain and 24-h urine samples were measured. The hippocampal pathological changes were observed by HE staining and electron microscopy afer the designed exposure.

    Results Compared with the control group, the weights of the F2 rats of the 120 and 240 mg/L NaF treatment groups afer eight weeks were decreased. Compared with the control group(7.06±0.79) μg/g, (1.89±0.23) μg/L, the brain fluorine(14.23±1.86), (18.15±1.98), (28.74±2.19) μg/g and urinary fluorine levels(11.36±0.91), (15.30±0.26), (18.67±2.01) μg/L of the NaF treated F2 rats were increased (P < 0.01). In the Morris water maze test, compared with the control group, the escape latencies in the 120 and 240 mg/L NaF treated F2 rats on the second day and third day and in all NaF treated F2 rats on the fourth day were increased (P < 0.05, P < 0.01); the tme to reach the original platorm was prolonged while the frequency of platorm crossings were decreased in the 120 and 240 mg/L NaF treated F2 rats (P < 0.05, P < 0.01). In the light-dark box experiment, the tme in the dark box(157.25±33.17), (209.38±10.98) s and the percentage of tme in the dark box(52.42±11.06)%, (69.79±3.67)% of the 120 and 240 mg/L NaF treated F2 rats were higher than those of the control group (P < 0.01), while the number of transitons of the 240 mg/L NaF treated F2 rats was reduced (P < 0.01). According to the optcal microscopy observaton with HE staining, compared with the control group, the NaF treated groups showed hippocampal neurons with nuclear pyknosis, hyperchromasia nucleus, and loss of structure. The electron microscopy observaton showed mitochondrial swelling, as well as Golgi and endoplasmic retculum expansion in hippocampal neurons of the NaF treated groups.

    Conclusion Contnuous fluorine exposure can damage the hippocampal neuron structure and reduce spatal learning and memory of F2 rats.

     

/

返回文章
返回