缺锌因素对阿尔茨海默病小鼠异氟醚麻醉后认知功能的影响

Effect of zinc deficiency factor on cognitive function after isoflurane anesthesia in mice with Alzhei-mer＇s disease

目的评价缺锌因素对阿尔茨海默病（AD）小鼠异氟醚麻醉后认知功能的影响。方法AD小鼠（APP/PS1转基因小鼠）144只，体重22～28 g，8～10月龄，采用随机数字表法分为6组（n＝24）：常锌组（ZA组）、常锌＋异氟醚麻醉组（ZA＋Iso组）、缺锌组（ZD组）、缺锌＋异氟醚麻醉组（ZD＋Iso组）、补锌组（ZT组）和补锌＋异氟醚麻醉组（ZT＋Iso组）。ZA组和ZA＋Iso组正常锌含量饲料和去离子水饲养2个月，ZD组和ZD＋Iso组低锌饲料（锌含量0.01‰）和去离子水饲养1个月，ZT组和ZT＋Iso组正常锌含量饲料和浓度为0.12‰的ZnSO4·7H2O水饲养2个月。ZA＋Iso组、ZD＋Iso组和ZT＋Iso组饲养结束后接受1.4%异氟醚麻醉2 h。于麻醉后24 h时，处死小鼠，取海马组织，采用ELISA法测定海马可溶性β-淀粉样蛋白40（Aβ40）和Aβ42、不可溶性Aβ40和Aβ42的含量，采用Western blot法测定海马总Aβ、Aβ40、Aβ42、tau pSer396、tau pSer262和tau pThr231的表达水平。于麻醉后24 h时进行水迷宫实验。结果ZA组与ZA＋Iso组比较、ZT组与ZT＋Iso组比较各项测定指标差异无统计学意义（P〉0.05）。与ZD组或ZT＋Iso组比较，ZD＋Iso组逃避潜伏期延长，空间探索时间缩短，海马Aβ42、tau pSer396、tau pSer262和tau pThr231表达上调，可溶性和不可溶性Aβ42含量升高（P〈0.05或0.01）。结论缺锌可加重AD小鼠异氟醚麻醉后认知损害，机制与促进海马Aβ聚集和tau蛋白磷酸化有关。

ObjectiveTo evaluate the effect of zinc deficiency factor on cognitive function after isoflurane anesthesia in mice with Alzheimer′s disease （AD）.MethodsOne hundred and forty-four APP/PS1 transgenic mice with AD, weighing 22-28 g, aged 8-10 months, were divided into 6 groups （n=24 each） using a random number table： zinc adequate group （group ZA）, zinc adequate plus isoflurane anesthesia group （group ZA＋ Iso）, zinc deficiency group （group ZD）, zinc deficiency plus isoflurane anesthesia group （group ZD＋ Iso）, zinc treatment group （group ZT） and zinc treatment plus isoflurane anesthesia group （group ZT＋ Iso）. The mice were fed a diet adequate in zinc and deionized water for 2 months in ZA and ZA＋ Iso groups.The mice were fed a diet low in zinc （0.01‰ zinc） and deionized water for 1 month in ZD and ZD＋ Iso groups.The mice were fed a diet adequate in zinc and 0.12‰ ZnSO4·7H2O water for 2 months in ZT and ZT＋ Iso groups.The mice underwent 2 h of anesthesia with 1.4% isoflurane starting from the end of feeding in ZA＋ Iso, ZD＋ Iso and ZT＋ Iso groups.At 24 h after anesthesia, the mice were sacrificed and hippocampal tissues were obtained for determination of the contents of soluble amyloid beta protein 40 （Aβ40） and Aβ42 and insoluble Aβ40 and Aβ42 （using enzyme-linked immunosorbent assay） and expression of total Aβ, Aβ40, Aβ42, tau pSer396, tau pSer262 and tau pThr231 （by Western blot）. Morris water maze test was performed at 24 h after anesthesia.ResultsThere was no significant difference in each parameter between group ZA and group ZA＋ Iso and between group ZT and group ZT＋ Iso （P〉0.05）. Compared with group ZD or group ZT＋ Iso, the escape latency was significantly prolonged, the space exploration time was shortened, the expression of hippocampal Aβ42, tau pSer396, tau pSer262 and tau pThr231 was up-regulated, and the contents of soluble and insoluble Aβ42 were increased in group ZD＋ Iso （P〈0.05 or 0.01）.ConclusionZinc deficiency can aggravate the impairment of cognitive function after isoflurane anesthesia in mice with AD, and the mechanism is related to the promotion of hippocampal Aβ aggregation and tau protein phosphorylation.