Lipoproteins and apolipoprotein patterns in rat plasma after liver injury induced by D-galactosamine

The effect of galactosamine administration on the concentration and composition of plasma lipoproteins was studied in female rats. After a single intraperitoneal injection of 3.48 mmol galactosamine/kg the following alterations occurred within 24 h: Disappearance of alpha-lipoproteins as shown by agarose electrophoresis, increase of abnormal lipoproteins in the beta- and pre-beta-region. These changes corresponded to a two- to three-fold increase of VLDL and LDL and a decrease of HDL to 20-30% of normal after sequential ultracentrifugation. When compared to control animals, galactosamine-treated rats exhibited an abnormal chemical composition of their plasma lipoproteins: A nearly total loss of cholesterol esters, but an increase of free cholesterol and phospholipids, particularly in the LDL and HDL density classes. Moreover, polyacrylamide gel electrophoresis in 8M urea revealed a clear diminution of all C-apoproteins in the VLDL and HDL density class and a complete disappearance of the A II band in the HDL fraction 24-48 h after galactosamine administration. These lacking apoprotein bands reappeared 72-168 h after galactosamine treatment. The same effects could be obtained by lower doses of galactosamine (2.32 and 1.16 mmol/kg, respectively) which led only to slight increases of hepatocellular enzymes in the plasma. It is concluded therefore, that galactosamine administration in experimental animals leads to profound, but reversible alterations in the synthesis and/or secretion of plasma lipoproteins.