Rc. Baybutt et A. Molteni, Dietary beta-carotene protects lung and liver parenchyma of rats treated with monocrotaline, TOXICOLOGY, 137(2), 1999, pp. 69-80
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.