The role of sodium cromolyn in treatment of paraquat-induced pulmonary fibrosis in rat.

Paraquat is a non-selective herbicide which is widely used in agriculture. It has potential of producing pulmonary fibrosis. In this study the therapeutic effect of different doses of sodium cromolyn on the development of paraquat-induced pulmonary fibrosis was investigated. In order to produce lung fibrosis, rats were given single oral dose of paraquat (40 mg kg(-1)). Two groups of animals were nebulised with 6 or 8 mg day(-1) cromolyn (divided into two doses per day) 5 days prior and 2 weeks after paraquat treatment. Control animals were given equivalent volume of normal saline and treated with cromolyn similar to the test groups. Rats were killed at the end of treatment course and lung tissues were tested histologically and biochemically. Histological examination of paraquat-treated animals showed marked infiltration of inflammatory cells in the alveolar spaces, septal thickening and fibrosis. Lesions were evident in many places of sections. Sodium cromolyn could markedly reduce such damages in lung tissue. Lung weight, hydroxyproline and collagen content of lung tissues were elevated significantly (P < 0.05) in paraquat group compared with control group. In cromolyn-treated groups such factors were near to control value and were significantly lower than paraquat group (P < 0.05). Results of this study indicate that sodium cromolyn can decrease the fibrogenic effect of paraquat on lung. Such effect may be due to the stabilising of mast cells and inhibition of inflammatory mediators by sodium cromolyn. Copyright 2002 Elsevier Science Ltd.