Effect of Dexamethasone drug on bleomycin -inducedpulmonary fibrosis in experimental rats

Pulmonary fibrosis (PF) is an irreversible and largely untreatable human disease encompasses a large group of chronic lung disorders associated with excessive remodeling, scarring, and fibrosis. The present study investigated the protective effect of dexamethasone administration against bleomycin-induced pulmonary fibrosis in adult male rats.A total of 40 male adult albino rats (Rattus norvegicous) weighing from 200-250 gm each, were divided into four groups of (10) animals each. The first group received a daily intraperitonial (i.p) injection of vehicle normal saline (0.5ml\animal, daily to end experiment), and served as control group. Animals in the second, third and fourth groups were administrated i.p. with bleomycin (15mg\kg\3times weekly for 3 wks), dexamethasone  1mg ∕ kg body weight (B/wt.) (diluted in 0.5ml saline) as a single dose daily for3wks and dexamethasone a combination with bleomycin simultaneously to end experiment, respectively.  The present study, displayed that the biochemical results determined the levels of Superoxide dismutase (SOD), Glutathion peroxidase (GSHpx) and Hydroxyproline(HYP) content in blood serum of animals. Where after oral administration of dexamethasone in combination with bleomycin, showed that dexamethasone significantly increase SOD P˂0.001 and GSHpx P˂0.001 levels, and decreased HYP P˂0.001 contents in blood stream of the rats in comparison with bleomycin group. On the contrary, study showed after intraperitonial injection of bleomycin alone, decreased level of SOD, GSHpx and increased of HYP content in blood serum of rats in comparison of control group. On the other hand, microscopical observations clarified that bleomycin injection showed that Most lung sections of BLM treated rats showed extensive damage of the lung tissue with loss of the normal alveolar architecture and majority of the alveolar walls were occupied by collagenous fibers, Results also clarified rupture of interalveolar septa forming large irregular emphysematous air spaces, Furthermore, lung sections of bleomycin – treated rats showed heavily infiltration with mononuclear inflammatory cells mostly lymphocytes, macrophages and moderate degeneration bronchioles epithelium. The  study clarified that lung sections from animals treated with both (BLM) and dexamethasone, was restored normal tissue, slight thickening, and space expansion, mild edema of the interstitium and alveolar spaces with clear terminal bronchioles. Nevertheless, still congested of interalveolar septa and scattered inflammatory cells. This investigation has clearly identified the importance role of dexamethasone as inhibitor factor on pulmonary fibrosis induced by bleomycin, therefore,  the findings may be offer one of therapeutic strategy to prevent the lung fibrosis in experimental rats model.