HMG-CoA reductase activity in the liver of rats with hereditary hypertriglyceridemia: effect of dietary fish oil. 
To assess the possible participation of liver microsomal 3-hydroxy-3-methylglutaryl coenzyme A (HMG-CoA) reductase in the hypocholesterolemic effect of fish oil (FO) in rats with hereditary hypertriglyceridemia (derived from the Wistar strain, obtained from VELAZ, Prague, Czech Rep.), male animals were fed a basal diet (BD) or a high sucrose diet (SD-63 cal %) with or without FO supplement (30 wt% n-3 polyunsaturated fatty acids) for 21 days.  The feeding with high sucrose diet resulted in increased HMG-CoA reductase activity; (P < 0.05).  However, FO added to the diet suppressed this stimulated enzymatic activity (919.05 +/- 76.86 vs. 614.05 +/- 48.53 pmol/min/mg prot.;  P < 0.05) and decreased cholesterol (CH) content in both serum and the liver of HTG rats fed basal as well as sucrose diet; (P < 0.05).  The results of the study demonstrated that the hypocholesterolemic effect of FO added to the diet was mediated under certain conditions, by affecting of HMG-CoA reductase activity and not only by its effect on specific receptors as demonstrated before.