Dietary beta-carotene protects lung and liver parenchyma of rats treated with monocrotaline

Some studies have indicated that the injury induced by the hepato- and pneu motoxin monocrotaline (EVICT) is in part mediated by oxidation. Because bet a-carotene is a potent antioxidant, we hypothesized that it would protect t he lung and liver parenchyma against MCT-induced injury. Twenty rats were a ssigned randomly to four groups. All rats were fed a standard AIN93G diet w ith or without beta-carotene. After I week on the purified diets, half of t he rats fed the control (standard) diet and half of the rats fed the beta-c arotene-supplemented diet were injected subcutaneously with 60 mg MCT/kg bo dy weight or its vehicle (water). All rats were sacrificed at 4 weeks. Hist ological examination showed that beta-carotene alone did not affect lung or liver structure. On the other hand, lungs of MCT-treated rats had severe f ocal pneumonia, extensive deposition of collagen in the septa, marked infla mmation of the small arteries and arterioles, and arterialization of the sm all venules. Livers of MCT-treated rats showed some fatty infiltration and diffuse hemorrhages, more prominent sometimes in the centrilobular area and sometimes in the periportal region. Concomitant treatment with beta-carote ne protected the lung parenchyma from the inflammatory reaction and the sep tal fibrosis, but did not prevent cardiac right ventricular hypertrophy and only slightly reduced the thickening of the wall of small arteries and art erioles. Incidence of steatosis and hemorrhages was decreased in the liver. These results indicate that MCT-induced pulmonary vascular remodeling occu rs in the absence of inflammatory cell infiltration. Furthermore, beta-caro tene prevented inflammation and protected the lung and liver parenchyma of MCT-treated rats. (C) 1999 Elsevier Science Ireland Ltd. All rights reserve d.