| [Objective]To study the protective effect of(Tertiary butylhydroquinone,tBHQ)and to explore the role and mechanism of Nrf2-ARE Signaling pathway on rats in acute silica dust exposure[Methods]1.SPF male Wistar rats were randomly divided into control group,model group and intervention group with 32 in each group.Rats in model group and intervention group were used to establish a rat model of silica dust with one time non exposed tracheal dust method.The intervention group was intervened once a day with tBHQ solution of 1%mass fraction,the control group was intervened once a day with 1%normal saline once a day.Eight rats in each group were put to death respectively at 3 days,14 days,28 days and 60 days.Lung tissue was fixed with paraformaldehyde,then embedded in paraffin,sectioned and stained with HE and Masson to observe the pathological changes.The contents of IL-l,TNF-α,TGF-βand HYP in rat lung tissue was determined with ELISA method,the contents of MDA and the activity of GSH-PX in lung tissue and serum of rats was determined by colorimetry.2.SPF male Wistar rats were randomly divided into control group,model group and intervention group with 32 in each group.Rats in model group and intervention group were used to establish a rat model of silica dust with one time non exposed tracheal dust method.The intervention group was intervened once a day with tBHQ solution of 1%mass fraction,the control group was intervened once a day with 1%normal saline once a day.Eight rats in each group were put to death respectively at 3 days,14 days,28 days and 60 days.The distribution of HO-1,NQO1 and Nrf2 protein in lung tissue of each group was determined by immunohistochemistry,the expressions of HO-1,NQOl and Nrf2 in lung tissues of each group was determined by Western blot method,the expression levels of HO-1,NQO1 and Nrf2 mRNA in lung tissue of rats was determined by RT-PCR.【Results】1.Pathological observation,in the control group,the alveolar structure was clear,the alveolar wall was thin,a small amount of inflammatory cells were infiltrated in the interstitium of the lung.In the model group,on the 3 days of tracheal dust,the alveolar wall septum of the model group thickened,the alveolar cavity and the interstitium were infiltrated with inflammatory cells,on the 14 days,the alveolar wall became sufficient thicker,the local alveoli began to fuse and the inflammatory cells infiltrated Iargely,on the 28th day,the alveolar structure was destroyed,most of the alveoli disappeared,and the number of macrophages increased,on the 60th day,pulmonary fibrosis began to occur,occupied by collagen fibers and fibroblasts.Compared with the control group,the contents of IL-1 in the lung tissue of both groups increased with time,and the contents of IL-1 in the lung tissue of the model group reached the highest level at 60 days,which is reached at 28 days in intervention group(P＜0.05).Compared with the control group,the contents of TGF-βand HYP in the lung tissue of both groups increased with time,which is reached at the highest level at 60 days(P＜0.05),the contents of TGF-βand HYP in the lung tissue of both groups increased with time,the contents of IL-1,TGF-Pand HYP in the intervention group was lower than that in the model group(P＜0.05).The contents of TNF-careached the highest level at 14 days,compared with the control group(P＞0.05),compared with the model group,the contents of MDA in the serum and lung tissues of intervention group at each time points increased with time(P＜0.05),compared with the model group,the contents of MDA in the serum and lung tissues of intervention group was lower than that in the model group(P＜0.05).Compared with the control group,the activity of GSH-PX in the serum and lung tissues of both groups decreased with time,except the 3rd(P＜0.05),compared with the model group,the GSH-PX activity of intervention group was higher than model.2.Immunity group experiment found that the expression of HO-1,NQ01 protein in control group was weakly and mainly scattered in the cytoplasm,the expression of Nrf2 protein was distributed in the cytoplasm and nucleus in both groups,the positive expression of HO-1,NQ01 and Nrf2 protein in the lung tissue increased,and which in intervention group was more and stronger than in model group,and the expression of Nrf2 protein cell nuclear was enhanced in the intervention group.Compared with the control group,the expressions of HO-1 protein in the lung tissue of both groups increased with time(P＜0.05),the expressions of HO-1 protein in the intervention group was more and stronger than in model group(P＜0.05)except 14 days.Compared with the control group,the expressions of NQO1 protein in the lung tissue of both groups increased with time except 3 days,except 14 days(P＜0.05),the expressions of NQO1 protein was more and stronger than in model group,except 14 days(P＜0.05).Compared with the control group,the expressions of Nrf2 protein in the lung tissue of both groups increased with time,except 3 days(P＜0.05).Compared with the control group,the expression of the Nrf2 protein in the nucleus of every group both increased with time,the expression of the Nrf2 protein in the nucleus of intervention group was higher than the model group,compared with the control group,the expression of the Nrf2 protein in the cytoplasm of every group decreased with time,the expression of the Nrf2 protein in the cytoplasm of the intervention group was weaker than that of the model group.Compared with the control group,the expression of the HO-1 mRNA and NQO1 mRNA increased at each time points(P＜0.05),the expression of the HO-1 mRNA,NQOl mRNA in the lung tissue of the intervention group was higher than that of the model group at each time point,except for the 3rd.Compared with the control group,the expression of the Nrf2 mRNA in the lung tissue increased with time.there was difference between every group except 3 days,except 3 days(P＜0.05),the expression of the Nrf2 mRNA in the lung tissue is higher than model group,there was difference between every group except 3 days,60 days.[Conclusions]In summary,our results demonstrated that the intervention of tBHQ not only alleviated oxidative stress in rats exposed to silica dust and improved the antioxidant capacity of the body,but reduced the contents of IL-1,TNF-a,TGF-α and HYP in lung tissue.These findings indicate that tBHQ intervention had a certain impediment and inhibition effect on the inflammation and fibrosis caused by acute silica dust exposure.Active Nrf2-ARE signaling pathway could inhibition the oxidative stress induced by the acute silica dust exposure,and this study we found that the intervention of tBHQ could activate the Nrf2-ARE signaling pathway by regulation the expression of the Nrf2,HO-1and NQO1. |
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