Inhibition Effect of Quercetin on Pulmonary Fibrosis in Rats

Objective To discuss the effect and mechanism of Quercetin in the process of pulmonary fibrosis in rats. Methods A total of 63 healthy Wistar rats were randomly divided into seven groups( each n = 9),and pulmonary fibrosis models were established using the bleomycin solution injected through nasal cavity of the rats in the A2 group( model establishment for 2 weeks),A4 group( model establishment for 4 weeks),A6 group( model establishment for 6weeks),B2 group( Quercetin treatment for 2 weeks),B4 group( Quercetin treatment for 4 weeks) and B6 group( Quercetin treatment for 6 weeks) except the rats in control group. Two weeks after the models were successfully established,rats in B2,B4 and B6 groups were given 10 mg /kg Quercetin solution with intraperitoneal injection for each day,while rats in A2,A4,A6 and control groups were given 5 ml /d saline with intraperitoneal injection. Three rats in each group were sacrificed 2,4 and 6 weeks after medication respectively,and values of indexes of blood gas analysis,lung coefficient,alveolitis scores,degree of pulmonary fibrosis,total and differential cell counts in bronchoalveolar lavage fluid( BALF) and the hydroxyproline( HYP) content of the lung tissues in all groups were compared,and then pathological changes of pulmonary tissues were observed using HE and Masson staining. Results Compared with those in control group,the Pa02 values in A2,A4 and A6 groups were significantly decreased( P 0. 05); values of lung coefficient,alveolitis scores and the degree of pulmonary tissues were significantly increased( P 0. 05); the total cell counts,neutrophils and lymphocytes in BALF were increased,among which there were significant differences between A6 group and control group( P 0. 05); the HYP contents in the pulmonary tissues were significantly increased( P 0. 05). Respectively compared with those in A2,A4 and A6 groups,the PaO2 values in B2,B4 and B6 groups were increased in different degrees( P 0. 05); the values of lung coefficient,alveolitis scores and the degree of pulmonary fibrosis were decreased,and the decreased value in B6 group was significant( P 0. 05),but the value was still higher than that in control group( P 0. 05); the values of total cell counts,neutrophils and lymphocytes in BALF were decreased,and the value in B6 group was significant( P 0. 05); the HYP contents in the pulmonary tissues were significantly decreased,and the decreased values in B4 and B6 groups were significant( P 0. 05); The pathological changes of pulmonary fibrosis indicated that structure of pulmonary tissues in control group was intact; the bronchial inflammatory infiltration was aggravated gradually,the bronchial mucosal was shed and the alveolar structure was seriously damaged in the A2,A4 and A6 groups; the degrees of alveolitis and pulmonary fibrosis were mitigated in the B2,B4 and B6 groups,especially in B6 group,and the degree of recovery was close to that in control group. Conclusion Quercetin can inhibit the process of pulmonary fibrosis in rats effectively and promote self-healing in pulmonary tissue.