Objective The aim of this study was to compare the interventional effects of polydatin given by different administration modes on experimental silicosis rats.

Methods Fifty SPF SD rats were randomly divided into five groups, namely the control group, silica model group, polydatin inhalation group, polydatin gavage group, and polydatin intraperitoneal injection group. There were 10 rats in each group. Among them, the control group did not have any treatment, the model group was only treated with silica molding, and the other 3 groups were treated with polydatin via different administration methods after silica molding. The general condition of rats in each group and the lung coefficient of each group were observed at 28 days and 56 days after dust treatment. Paraffin sections of rat lung tissue were stained with hematoxylin-eosin (HE) and Masson staining. The kit was used to detect the content of hydroxyproline (HYP) and malondialdehyde (MDA) in the lung tissue of rats in each group, and the degree of lung inflammation and pulmonary fibrosis in each group of rats was evaluated.

Results At day 56 after dust exposure, the lung coefficient of rats in the model group was significantly increased (P < 0.001) compared with the control group; compared with the model group, the lung coefficient of rats in the intraperitoneal injection group was decreased (P < 0.05). The results of HE staining of lung tissue of rats in each group showed that the alveolar wall was thin and the alveolar structure was normal in the control group on the 28th and 56th days, and no collapse was seen; compared with the control group on the 28th day, the alveolar wall of the rats in the 28th day model group was significantly thickened, the alveolar septum was widened, and a large number of inflammatory cells infiltrated the alveolar cavity; compared with the 28th day model group, the alveolar structure of each intervention group of polydatin was relatively normal. At day 56, compared with the control group, the alveolar wall of fibroblasts and fibroblast hyperplasia were further thickened in the model group; compared with the model group, the alveolar spacing in the intraperitoneal injection group, gavage group, and nebulized inhalation group was reduced. The Masson staining examination of rat lung tissue showed that, compared with the control group, the lung tissue of the model groups on the 28th and 56th days had blue cord-like collagen fiber hyperplasia. The results of collagen volume analysis showed that on the 28th and 56th days, the collagen volume integration number of the model group increased significantly compared with the control group; compared with the model group, the collagen volume fraction of all three groups of polydatin-treated rats decreased (P < 0.01). Such effects were observed to be more pronounced in rats with the intraperitoneal injection compared to those of the other two groups. On the 56th day after treatment, the content of HYP in the lung tissues in all treated groups increased compared with the control group (P < 0.05); compared with the model group, the content of hydroxyproline decreased in the intraperitoneal injection group, gavage group, and nebulized inhalation group (P < 0.05). On the 28th day after treatment, there was no significant difference in the concentration of malondialdehyde in the serum of each group (P = 0.140). On the 56th day after treatment, compared with the control group, the levels of MDA in the serum of the model group, the gavage group, and the aerosol inhalation group increased (P < 0.05); the content of MDA in the intraperitoneal injection group, gavage group, and nebulized inhalation group decreased (P < 0.05) compared with the model group, among which the MDA content in the intraperitoneal injection group had the best amelioration effect.

Conclusions Polydatin, optimally administered by intraperitoneal injection, could effectively decelerate silicosis progression in SD rats, possibly via its anti-inflammatory and anti-fibrotic effects.