Comparison of the effects of basal and methionine-supplemented recovery diets on the liver of ethionine-pretreated rats.

Alterations in the liver of rats during ethionine administration and subsequent recovery on basal or methionine-supplemented diets were examined by light and electron microscopy and by the point counting technique. After administration of 1% DL-ethionine diet for 34 days, adult female rats showed a significant decrease (P less than 0.01) in the percentage volume of hepatocytes and a significant increase (P less than 0.002) in the percentage volume of duct cells compared with control animals. When the carcinogen diet was replaced by either basal or methionine-supplemented diet, the percentage volumes of proliferated duct cells fell. The hepatocytes appeared almost normal in the rats on basal recovery diet, whereas those on methionine diet showed extensive fat accumulation in the central hepatocytes. Similar lipid deposition was observed in rats given either methionine plus ethionine diet or basal diet followed by methionine diet as a recovery diet. The percentage volumes of hepatocytes and duct cells in rats transferred to basal recovery diet did not differ significantly from those placed on methionine diet or on methionine plus ethionine diet. Some possible causes of methionine-induced fat deposition are discussed.