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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 temporal distribution characteristics of nano-silica (SiO 2) in rats after one-time non-exposure tracheal instillation. Methods Male Wistar rats without specific pathogen were randomly divided into control group and experimental groups of 1, 3, 5, 7, 14, 21 and 28 days, with 6 rats in each group. One time non-exposed tracheal instillation method was used. The rats were treated with 1.0 mL of nano-SiO 2 suspension with the concentration of 50.00 g / L, while the rats in the control group were given no treatment. The serum, lung, spleen, liver and kidney tissue of each group were collected at the corresponding time points after the exposure to dust, and the silicon levels in the samples were determined by inductively coupled plasma-optical emission spectrometry. The lungs of rats were taken for pathological observation, and the distribution of nano-SiO 2 particles was observed by polarized light microscope. RESULTS: Pulmonary tissues were mainly exudative inflammatory reaction 1 ~ 7 days after the nano-SiO 2 was dyed, and mainly proliferated from 14 to 28 days after the exposure to dust. On the 28th day, rats in experimental group Lung tissue visible cell nodules. Under the polarized light microscope, the distribution of the obvious nano-SiO 2 particles in the lung tissues of the experimental rats at 1 d after the dusting showed a trend of decreasing with the increase of the observation time, and after 21 and 28 d of dusting Very rare nano-SiO 2 particle distribution. The levels of silicon in the serum, lung and spleen of the experimental group all reached the peak on the 1st day after dust exposure, and were time-dependent 3 to 7 days (serum) or 3 to 14 days (lung and spleen) after dusting Sexual decline, and returned to normal levels. In the experimental group, there was no statistically significant increase of silicon in the liver and kidney (P> 0.05) between 1 and 5 days after exposure to dust, all of which showed statistical significance (P <0.05), and reached the peak at 14 and 21 d after dusting, respectively, and then dropped to the normal level at 28 days after dusting. The levels of silicon in the lung, spleen, liver and kidney in experimental groups were all higher than those in serum (P <0.05). The levels of silicon in lung and spleen were higher than those in liver and kidney 1-5 d after dying ). The contents of silicon in lung and spleen were lower than those in liver and kidney 14 ~ 28 d after dusting (P <0.05). CONCLUSIONS: Nano-SiO 2 can cause lung injury in rats through dust exposure of the respiratory tract. In the first 5 days after the dust exposure, it mainly distributes in the lung and spleen, and mainly distributes in the liver and kidney at 14-28 days.