百草枯中毒大鼠肺纤维化与内质网应激的关系

The relationship of endoplasmic reticulum stress with paraquat induced lung fibrosis in rats

目的探讨百草枯（PQ）中毒后大鼠发生肺纤维化与内质网应激的关系。方法将100只雄性sD大鼠按随机数字表法分为对照组（10只）和染毒组（90只），20％PQ溶液灌胃染毒后2、6、12、24、48、72、96、168、336h处死动物取肺组织，苏木素-伊红（HE）染色和Masson染色观察肺组织病理学变化；免疫组化检测糖调节蛋白78（GRP78）表达；测定肺组织丙二醛（MDA）含量；提取肺组织总蛋白，用蛋白质免疫印迹试验（Westernblotting）检测α-平滑肌肌动蛋白（d-SMA）和GRP78的蛋白表达。结果HE及Masson染色结果提示染毒组出现肺组织炎性细胞浸润和胶原纤维沉积，随中毒时间延长，肺纤维化逐渐加重。染毒后2hMDA水平及α-SMA、GRP78蛋白表达均较对照组明显升高[MDA（nmol／mg）：1．38±0．18比0．85±0．05，α-SMA：0．23±0．01比0．14±0．03，GRP78：0．72±0．02比0．37±0．06，P〈0．05或P〈0．01]，随时间延长，MDA水平及α-SMA蛋白表达逐步升高，GRP78蛋白表达于染毒72h后显著下降。结论PQ中毒大鼠肺内质网应激标志性蛋白GRP78和成纤维细胞表型标志物α-SMA均增高，提示内质网应激在PQ中毒引起的肺纤维中发挥重要作用。

Objective To investigate the relationship between pulmonary fibrosis and endoplasmic reticulum stress （ERS） in rats with paraquat poisoning. Methods One hundred male Sprague-Dawley （SD） rats were randomly divided into control group （n =10） and paraquat poisoning group （n =90）. The animals were sacrificed by exsanguination at 2, 6, 12, 24, 48, 72, 96, 168, 336 hours after administration with 20% parquat solution. The paraffin sections of lung tissue were stained with hematoxylin-eosin （HE） and Masson trichrome to observe the pathological changes. Glucose-regulated protein 78 （GRP78） was determined by immunohistochemistry, and malondialdehyde （MDA） of lung tissue was measured. The total protein of tissue was abstracted, and the α -smooth muscle actin （ α -SMA ） and GRP78 was detected by Western blotting. Results HE and Masson staining demonstrated inflammatory infihration and collagen deposition in the lung after paraquat administration with a tendency of exaggeration with time, and finally resulted in fibrosis. The expressions of MDA, α-SMA and GRP78 in the lung tissue were significantly increased 2 hours after paraquat administration compared with those of control group （MDA （nmol/mg）： 1.38 ±0.18 vs. 0.85 ±0.05, α-SMA： 0.23 ±0.01 vs. 0.14 ±0.03, GRP78：0.72 ±0.02 vs. 0.37 ±0.06, P〈0.05 or P〈0.013, and the expressions of MDA and α -SMA were gradually increased with time. GRP78 protein expression was decreased at 72 hours after paraquat administration. Conclusion The results reveal that the expressions of α -SMA and GRP78 in paraquat poisoning group are up-regulated, suggesting ERS plays an important role in paraquat induced-pulmonary fibrosis.