气管滴注纳米二氧化硅在大鼠体内时间分布特征

Time distribution characteristics of silica nanoparticle intratracheal-instillation in rats

目的观察纳米二氧化硅(SiO_2)经气管一次性非暴露式滴注后在大鼠体内的时间分布特征。方法无特定病原体级雄性Wistar大鼠随机分为对照组和1、3、5、7、14、21、28 d实验组,每组6只,采用一次性非暴露式气管滴注法,各实验组大鼠均予质量浓度为50.00 g/L的纳米SiO_2混悬液1.0 mL处理,对照组大鼠不予任何处理。分别于染尘后相应时间点采集各组大鼠的血清和肺脏、脾脏、肝脏、肾脏组织,采用电感耦合-等离子体发射光谱法测定样品中硅元素的水平。取大鼠肺组织进行病理学观察,采用偏振光显微镜观察纳米SiO_2颗粒分布情况。结果大鼠肺组织在纳米SiO_2染尘后1~7 d出现以渗出性炎症反应为主的改变,在染尘后14~28 d以增生性炎性病变为主;28 d实验组大鼠肺组织可见细胞性结节。偏振光显微镜下,各实验组大鼠肺脏组织中于染尘后1 d可观察到明显纳米SiO_2颗粒物分布,其后呈现随着观察时间的增加而减少的趋势,至染尘后21和28 d极少见纳米SiO_2颗粒物分布。实验组大鼠血清、肺脏和脾脏组织中硅元素水平均于染尘后1 d升高达到峰值,在染尘后3~7 d(血清)或3~14 d(肺脏、脾脏)呈现时间依赖性的下降,且恢复正常水平。实验组大鼠肝脏和肾脏的硅元素水平在染尘后1~5 d均无出现有统计学意义的升高(P>0.05);均于染尘后7 d才出现有统计学意义的升高(P<0.05),分别于染尘后14和21 d升高达到峰值,其后下降,至染尘后28 d仍未恢复正常水平。各实验组大鼠的肺脏、脾脏、肝脏和肾脏硅元素水平均高于血清(P<0.05);在染尘后1~5 d肺脏、脾脏硅元素水平均高于肝脏和肾脏(P<0.05),在染尘后14~28 d肺脏、脾脏硅元素水平均低于肝脏和肾脏(P<0.05)。结论纳米SiO_2经呼吸道染尘可导致大鼠出现肺损伤;染尘后1~5 d主要分布于肺脏和脾脏,在14~28 d主要分布于肝脏和肾脏。

Objective To observe the time distribution characteristic of silica nanoparticles in rats after one-time intratracheal infusion. Methods Specific pathogen free male Wistar rats were randomly divided into one control group and7 experimental groups according to different time of intratracheal infusion（ 1,3,5,7,14,21 and 28 days）,6 rats in each group. The experiment groups were intratracheally instilled with 1. 0 mL silica nanoparticle suspension（ mass concentration 50. 00 g/L）. The control group was not given any treatment. Rats were sacrificed and their organ tissue samples such as serum,lung,spleen,liver and kidney were collected at different time points. The silicon levels of tissues were determined by inductively coupled plasma optical-emission spectrometry. The histology of rat＇s lungs was observed by optical microscope and the location of silica in lungs was observed by polarization microscope. Results After exposure to silica nanoparticles for 1-7 days,the changes of rats＇ lung tissue was mainly exudative inflammation. The changes of lung was proliferative inflammatory lesions after 14-28 days of exposure to silica nanoparticles. The visible nodules of cells were observed in the lung tissue in 28 days experiment group. The distribution of silica nanoparticles was observed obviously in the lung tissues of rats of 1 day experiment group under the polarizing microscopy. The tendency decreased with the increase of observation time. Silica nanoparticles were rarely seen 21 and 28 days after intratracheal infusion in rats. The silicon levels of serum,lung and spleen tissues reached the peak in 1 day after silica nanoparticles instillation,then dropped in 3-7 days（ serum） or 3-14 days（ lung and spleen tissues） and went back to that of the control group＇s. The level of silicon in the livers and kidneys of rats in the experimental groups showed no significant increase in the level of 1-5 day after the instillation（ P〈0. 05）,and showed significant increase in the level of 7 day（ P〈0. 05）. The level reached its peak on time points of 14 and 21 days after the instillation,and subsequently decreased,and didn＇t returned to normal till the 28 th day. The silicon levels of the lungs,spleens,livers and kidneys were all higher in rats than that of serum（ P〈0. 05）. The silicon levels of the lungs and spleens were higher than that of the livers and kidneys after instillation for1-5 days（ P〈0. 05）. The silicon levels of the lungs and spleens were both lower than that of the livers and kidneys after instillation for 14-28 days（ P〈0. 05）. Conclusion Silica nanoparticles can cause lung injury when instilled intratracheally in rats. After instillation,silica nanoparticles were mainly distributed in the lungs and spleens after 1-5 days and distributed in the livers and kidneys after 14-28 days.