Abstract: Objective To investigate the protective and cure effects of dexamethasone on bleomycin-induced pulmonary fibrosis.Methods32 rats were randomly divided into the control group (C-group, n=8), injury group (I-group, n=12) and dexamethasone group (D-group, n=12). The acute pulmonary model was established by intratracheal injection of bleomycin with rats of the I-group and D-group; while rats of the C-group injected with distilled water. After that, rats of the D-group were injected with dexamethasone sodium phosphate in intraperitoneal every day, those of the C-group and I-group were injected with saline. The animals were killed on the 3rd, 7th, 14th, and 27th days after treatment, and tests of bronchoalveolar lavage fluid (BALF), total lung collagen content and lung tissue processing were performed.ResultsPathological evidence of the I-group rats demonstrated that the alveolar compartment companied with massive inflammatory cell invasion and a number of myofibroblast proliferation became more thick. However, lung injury in the D-group rats got better than that in the I-group. Neutrophil percentage achieved peak in both I-group and D-group on the 7th day. But the neutrophil ratio in the D-group was significantly lower than that of the I-group on the 7th day ( P<0.05) and the 14th day ( P<0.01). Total lung collagen content achieved peak on the 14th day both in I-group and D-group, but that of the I-group was significantly higher than that of the C-group ( P<0.01) and the D-group was significantly lower than the I-group ( P<0.01).ConclusionDexamethasone plays a protective and cure role in lung fibrosis by efficiently inhibiting the gather and invasion of neutropils and restraining the increase of collagen secreted by proliferous fibroblasts.

Key words: dexamethasone, pulmonary fibrosis, collagen, hydroxyproline assay