| Objective: To observe the expressions of ER associated degradation protein 1(Derlin-1) and glucose regulated protein 78(GRP78) in paraquat-induced pulmonary fibrosis of rats, and to further investigate the influence of Derlin-1 and GRP78 on the occurrence and development of paraquat-induced pulmonary fibrosis.Methods: Fifty male SD rats were randomly divided into control group with 10 rats and paraquat injection group(PQ) with 40 rats. After the 20% concentration PQ were diluted at the proportion of 1:50, Rats in model group were intraperitoneal injected with one dose of 15.0mg/kg PQ, meanwhile the control group were intraperitoneal injected with the same does of saline. On the basis of exposure time, the PQ group was divided into four subgroups: 1D, 7D, 14 D, 21 D. Excluding the rats which do not meet the standards and the death ones after injected with PQ, on day 1,day 7,day 14,day 21, each day 6 animals in PQ group were put to death, while the NS group’s were all put to death on day 1 and then 6 animals were randomly picked into the last result and the lung tissues of these rats were saved. Observe the rats’ behavior after PQ injected, the morphology of lung tissues and lung coefficient; watch alveolitis and pulmonary fibrosis after the lung were stained by HE and Masson, and score them. Then observe the expressions of Derlin-1 and GRP78 in lung by immunohistochemistry, and check Derlin-1’s expression in lung homogenateusing Elisa.Results: 1、General condition: Rats in control group were in good spirit with good appetite, breathing smoothly, and moving freely, while the rats in PQ group were exposed with varying degrees of listlessness, breathing hard, cyanosis, eating less, or even death. On day 1 to day 7, the above symptoms become more serious obviously and mortality rate was high. On day 7 to day 21, the rats were relieved in spirit, eating more, but still in difficulty breathing. 2、The gross morphology of lung tissue : of the control group were pink, soft texture, of the PQ group had varying degrees of congestion, edema, focal pulmonary consolidation. And in the early stage, pulmonary congestion and edema were obvious, while in the late stage shows hard texture, fibrosis. Counting the lung coefficient of each group, all the scores of 1D、7D、14D groups were higher than that in control group(P<0.05), and both 14D’ and 21D’s were lower than 7D’s(P<0.05). However, the compare between the score of 21 D and of control group(P>0.05) didn’t show any statistical significance. 3、The result of HE staining and alveolitis scores: alveolar structural of rats in normal group was integrity and clear, of the PQ ones’ were unclear with alveolar wall fracture, hyperemia, edema, inflammatory cell infiltration, and in the late period there were fibroblast and collagen deposition. The scores of pulmonary alveolitis in the PQ group were more prominent compared to control group(P<0.05), which in 1D group alveolitis score increased significantly, 7D’ was the highest, 21D’s was alleviated. 4、The extent of Masson staining and the fraction of pulmonary fibrosis: the NS group had normal structure. The PQgroups showed gradually increased blue pigmentation collagen fibers with the extension of time,and partly consolidation、fibrosis. The fraction of pulmonary fibrosis in PQ group were all higher than the control group, and when compared to control group 7D、14D、21D had statistically significant(P<0.05),while the 1D group was no statistically significant(P>0.05). And the exposure time longer the score got higher. 5、Expression of Derlin-1 : IH showed that, Derlin-1 mainly expressed in the cytoplasm of bronchial epithelial cells, alveolar epithelial cells and vascular endothelial cells. Elisa and IH both suggested that the expression of Derlin-1in the control group was the lowest, and in the PQ group, it was increased first and then decreased, on day 14, it was the highest. 21 D group decreased but still higher than 1D and 7D. The differences between the exposed group and the normal group was statistically significant(P<0.05). 6、Expression of GRP78: IH showed that GRP78 was mainly expressed in bronchial epithelial cells, alveolar cells and endothelial cell cytoplasm. In 1D group the expression began to increase, reached the highest point in 7D group, then the expression in 14 D group began to decline but still higher than 1D, while 21 D group’s expression decreased significantly when compared to 14D(P<0.05), but the average expression level of the exposure group were higher than that in control group, comparing each PQ group with the control group, the difference was statistically significant(P<0.05).Conclusion:1、The model of pulmonary fibrosis of rats can be successfully constructed by Paraquat poisoning. 2、The endoplasmic reticulum stress reacts in paraquat poisoning in rats. 3、With the prolonged of the PQ poisoning time,the expression of Derlin-1 and GRP78 in lung tissue changes regularly. 4、Derlin-1 and GRP78 may play an important role in the occurrence and development of pulmonary fibrosis. |
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