OBJECTIVETo investigate the effects of total flavonoids from astragalus complanatus (FAC) on paraquat poisoning-induced pulmonary fibrosis in rats.

METHODSThe rats were divided into six groups randomly: control group, paraquat group, prednisolone group and FAC low-dose, middle-dose, high-dose group. Pulmonary fibrosis model was replicated by intratracheal injection of paraquat. In the mext day,the rats were treated by intragastric administration once a day. After 28 days, the rats were sacrificed. The lung index and the levels of HYP and T-AOC were measured, and the pathologic changes of the lung tissue were obtained by HE staining. The levels of TGF-β, Smad2, α-SMA protein were analyzed by Western blot.

RESULTSFAC improved the activity of T-AOC in serum and reduced pulmonary index and the content of HYP as well (P<0.05 or P<0.01), the alveolitis and fibrosis extent were attenuated. The expression of Smad2 significantly decreased in groups of FAC low-dose, middle-dose and high-dose (0.31±0.11, 0.45±0.12 and 0.30±0.05) as compared with that of the PQ group (0.85±0.34) (P<0.05). The expression of α-SMA significantly decreased in groups of FAC low-dose, middle-dose and high-dose (0.31±0.11, 0.35±0.07 and 0.32±0.10) as compared with that of the PQ group (0.45±0.08) (P<0.05). The expression of TGF-β significantly decreased in groups of FAC low-dose, middle-dose and high-dose (0.35±0.04, 0.27±0.05 and 0.18±0.04)as compared with that of the PQ group (0.63±0.11) (P<0.05).

CONCLUSIONFAC can alleviate PQ-induced pulmonary fibrosis in rats through inhibiting TGF-β/Smad signaling pathway.