HYPERCHOLESTEROLEMIA INDUCED BY CHOLESTEROL-ENRICHED OR CYSTINE-ENRICHED DIETS IS CHARACTERIZED BY DIFFERENT PLASMA-LIPOPROTEIN AND APOLIPOPROTEIN CONCENTRATIONS IN RATS

This study examined the effects of diet-induced hypercholesterolemia o n plasma apolipoprotein (apo) concentrations and hepatic apolipoprotei n mRNA levels in rats. Hypercholesterolemia was induced by feeding rat s diets containing an excess of either cholesterol or cystine. After c holesterol feeding, plasma apo E and apo B concentrations were lower ( -65%, P < 0.001) and greater (+39%, P < 0.01), respectively, compared with control diet-fed rats. After cystine feeding, plasma apo B and ap o E concentrations were greater (+46%, P<0.01 and +75%, P<0.001, respe ctively) and plasma apo A-IV concentration was lower (-29%, P < 0.001) than in rats fed control diet. After cholesterol or cystine feeding, a tendency (one-way ANOVA, P = 0.08) for greater apo B mRNA level (+42 % and +47%, respectively) was observed compared with control diet-fed rats. No difference emerged between groups for apo E and apo A-I mRNA levels. An opposite effect of cholesterol and cystine feeding was show n for apo A-IV mRNA level, i.e., higher after cholesterol feeding (+47 %, P < 0.05) and lower after cystine feeding (-65%, P < 0.01). From th is work, it seems that hypercholesterolemia induced by dietary cholest erol or by increased cholesterogenesis in cystine-fed rats is characte rized by different plasma lipoprotein and apolipoprotein concentration s and is associated with different apolipoprotein gene expression in t he liver.