Journal of Lipid Research, Vol 25, 813-820, Copyright © 1984 by Lipid Research, Inc.
Hepatic triacylglycerol synthesizing activity during progression of alcoholic liver injury in the baboon
MJ Savolainen, E Baraona, P Pikkarainen and CS Lieber
To study the effects of alcoholic liver injury on the ability of ethanol to
promote hepatic fat accumulation and hyperlipemia, baboons were pair-fed
liquid diets containing 50% of energy either as ethanol or as additional
carbohydrate (controls) for 1 to 7 years. Alcohol consumption produced
triacylglycerol accumulation in the liver, hypertriacylglyceridemia, and
various degrees of liver injury, including cirrhosis. At the early stages
of fatty liver (with or without perivenular fibrosis), there was increased
activity of microsomal diacylglycerol acyltransferase and of both
microsomal and cytosolic phosphatidate phosphohydrolase, with no changes in
glycerol-3- phosphate acyltransferase. With progression of the liver injury
and development of septal fibrosis and/or cirrhosis, the rate of hepatic
triacylglycerol accumulation and the magnitude of the hyperlipemia
decreased, despite continuous ethanol intake. These changes were associated
with disappearance of the increases in microsomal diacylglycerol
acyltransferase and cytosolic phosphatidate phosphohydrolase activities,
whereas those of microsomal phosphatidate phosphohydrolase remained
elevated and glycerol-3-phosphate acyltransferase was unaffected. Thus,
changes in the activity of two enzymes of the triacylglycerol-synthesizing
pathway, namely the microsomal diacylglycerol acyltransferase and the
cytosolic phosphatidate phosphohydrolase, may contribute to the differences
in the rate of hepatic triacylglycerol accumulation and the degree of
hyperlipemia during progression of the alcoholic liver damage.