Objective:To study the Pathological changes in lungs of rats infected with Pneumocystis carinii pneumonia after treatment with bilodalide(BL). Methods:PCP rat models were established of hypodermic injection of dexamethasone twice a week for 6 weeks. The PCP rats were treated with BL 30mg/(kg.d)×8days and killed to obtain lungs. Pathological changes in lung tissues were observed under light and electron microscope .Infected and normal rats were established as controls. Results: The number of Pc cysts was markedly reduced in the lung print smear and inflammation in the lung was lightened. The investigation of thinner lung tissue section by transmission electronic microscope showed that the Pneumocystis carinii treated with bilobalide had formation of vacuoles in trophozoites

swelling and destroying of cell organ

rupture of cytomembrane and some high density electronic granulae were investigated in the cytoplasm. Membrane of cyst was destroyed too. Conclusion:Bilodalide can kill Pc and alleviate inflammation in the lung tissues of PCP rats.