Antioxidant effects of oral N-acetylcysteine on silica-exposed rats

Objective To examine the antioxidant therapy effects of oral N-acetylcysteine(NAC) in silica-exposed rats.Methods A total of 96 Wistar rats were randomly divided into groups of silica-exposed only(model),silica-exposed and NAC treated and healthy control.The dose of 500mg·kg-1 NAC was orally given to Wistar rats once a day from one week prior to the single intratracheal instillation of silica dust suspension(model and treatment groups) or saline(control group).NAC treatment was continued 2 days after the instillation of silica dust.The lung samples of rats were collected in the 3rd,7th,14th and 28th day of silica post-instillation.The pathological changes of lung tissues were evaluated by the methods of HE and Masson staining.The extent of alveolar fibrosis was assessed by the semi-quantitative histological scores of Ashcroft method.The contents of hydroxyproline(HYP) and malondialdehyde(MDA) in lung tissue were measured per manufacturer′s instruction.Results The pathological changes of alveolitis and pulmonary fibrosis were mitigated in the rats of treated group compared with that in the rats of model group.The semi-quantitative scores of histological assessment showed less collagen deposition in the rats of treated group than in the rats of model group(P0.01).The level of MDA in model group increased significantly at all tested time points(P0.01) and the maximum value appeared in the 7th day of silica post-instillation.The level of HYP increased from the 7th day and the maximum value appeared in the 28th day of silica post-instillation in model group(P0.01).The contents of HYP and MDA decreased significantly in the lung tissues of treated group at different tested time points(all P0.01).Conclusion Oral N-acetylcysteine improves pulmonary antioxidant effects and reduces silica-exposed lung damages in rats.