孕哺期及成年期饮水高氟暴露致子代大鼠学习记忆损伤及大脑海马组织凋亡与自噬

Learning and memory damage,apoptosis and autophagy in hippocampal among rats exposed to high fluoride from pregnancy, lactation to adult stage

目的研究饮水途径高氟暴露对大鼠学习记忆能力的影响,并探索凋亡和自噬在高氟致海马组织损伤的作用。方法妊娠的清洁级SD大鼠饮用含氟量不同(10、50、100 mg/L NaF)的自来水,子代鼠从出生至断乳前通过母乳接触NaF;断乳后,各组子代鼠接受与亲代相同的氟暴露处理至出生后第60天,以Morris水迷宫试验检测大鼠的空间学习记忆能力,通过Western blot方法检测海马组织中与凋亡相关蛋白(Bcl-2和Bax)以及与自噬相关蛋白(Beclin-1、mTOR、LC3-Ⅱ和p62)的表达水平。结果与对照组相比,雄性子代大鼠100 mg/L NaF染毒组到达平台的潜伏期和路径距离明显增加(P<0.05),雌性子代大鼠100 mg/L和50 mg/L NaF染毒组到达平台的潜伏期和路径距离也明显增加(P<0.05);雌、雄子代大鼠100 mg/L和50 mg/L NaF染毒组子代大鼠海马组织中Bax、Beclin-1和LC3-Ⅱ蛋白表达水平均明显上调(P<0.05),Bcl-2、mTOR和p62蛋白表达水平均明显下调(P<0.05)。结论孕哺期及成年期饮水高氟暴露致子代大鼠空间学习记忆能力的损伤可能与海马组织自噬作用增强有关,同时可能伴随海马组织凋亡发生。

Objective To understand the apoptosis and autophagy in hippocampus and the learning and memory damage induced by high fluoride exposure from pregnancy to adult stage in rats. Methods Healthy adult SD rats were treated with fluoride through drinking water at the doses of 10, 50 and 100 mg/L NaF respectively to lactation. And after weaning, the offspring in each group exposed to NaF through drinking water at the same levels as their mothers exposed, for 60 days. At the end of the water maze test, and the hippocampal tissues were collected. The rats’ learning and memory capacity, and autophagy mainly related protein in the hippocampus(Beclin-1, mTOR, LC3-Ⅱ, p62) as well as representatives of the Bcl-2 family main protein(anti-apoptotic proteins the Bcl-2 and pro-apoptosis proteins Bax) expression level were determined by using the Morris water maze test, and Western blot techniques. Results Compared with the control group, the incubation period and distance of arriving platform increased in male rats in 100 mg/L NaF group and in female rats in 100 mg/L and 50 mg/L NaF groups(P<0.05). Compared with the control group, in 100 mg/L and 50 mg/L NaF groups, the protein expression of bax, beclin-1 and LC3-Ⅱ(P<0.05) were up-regulated and the protein expression of Bcl-2, mTOR and p62 were down-regulated significantly(P <0.05). Conclusion The learning and memory damage in rats exposed to high fluoride may be related to autophagy enhancement in hippocampal tissue, accompanied by apoptosis of hippocampal tissue.