Objective To explore the regulation role of quercetin on the expression of transforming growth factor beta 1(TGF-β1) signal transduction pathway in the lung of silicotic rats.
Methods Totally 75 specific-pathogen-free (SPF) maleWistar rats were randomly divided into three groups:a control group,a model group,and a quercetin group.The rat silicosis modelwas induced by intratracheal instillation of silicosis (250 mg/kg),the quercetin group was treated with 1.0 mL saline containg 50 mg/kgquercetin after injection of SiO2,while the rats in the control group were given saline in the same condition.The rats in all groupswere put to death on the 3th,7th,14th,21th,28th days after the silicosis model established.The content of total collagen in lung tissuewas determined by hydroxyproline kits.The expression of TGF-β1 protein and p-Smad3/7 in lung tissue samples were evaluatedby immunohistochemistry and Western blot technique.
Results The contents of total collagen in the model group were 6.28,13.11,11.59 times of the values in the controls in the same periods respectively (P<0.01).The contents of total collagen in thequercetin group were 43.05%,38.92%,and 37.40% of the corresponding values in the model group in the same periods respectively (P<0.01).The expression levels of TGF-β1 were lower in the quercetin group than in the model group in the same periods andhigher than in the control group (P<0.01 and P<0.05,respectively).The expression levels of p-Smad3 were higher in the modelgroup than in the quercetin group and in the control group in the same periods (P<0.01),but were lower in the quercetin groupthan in the model group and higher than in the control group in the same periods (P<0.01).The expression levels of p-Smad7 werelower in the model group than in the control group and in the quercetin group in the same periods (P<0.01),but were higher in thequercetin group than in the model group or in the control group at each designed time spot (P<0.01).
Conclusion Quercetincould decrease the expression of Smad3,increase the expression of Smad7,and then inhibit the collagen protein in silicotic rats.
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