Hepatic and intestinal formation of polar sterols in vivo in animals fed on a cholesterol-supplemented diet

Abstract

In rats fed on a diet containing 1% cholesterol for 24 h, the decrease in hepatic non-saponifiable lipid synthesis, cholesterogenesis and 3-hydroxy-3-methylglutaryl-CoA (HMG-CoA) reductase activity was accompanied by an increase in the proportion of newly synthesized polar sterols in vivo. In these animals there was also a strong inverse correlation between the proportion of polar sterols in the non-saponifiable lipid and hepatic HMG-CoA reductase activity. A similar correlation was not observed in animals fed on a normal diet. Cholesterogenesis in the intestine was not as sensitive to inhibition by dietary cholesterol as was that in the liver, and there was no increase in the polar-sterol content of the newly synthesized non-saponifiable-lipid fraction.

Oxysterols: Modulators of Cholesterol Metabolism and Other Processes

“…Marco de la Calle and co-workers (614,615) studied the incorporation of tritium into hepatic sterols of liver of male Wistar rats at 1 h after the intraperitoneal injection of 3 H 2 O. Significant incorporation of the labeled hydrogen into "polar sterols" was reported.…”

“…Chol feeding (1% in diet for 24 h) was reported to decrease HMG-CoA reductase activity in liver, to decrease the incorporation of the labeled hydrogen into NSL and Chol, and to increase the percentage of 3 H of NSL that was associated with polar sterols. In the Chol-fed animals, strong inverse relationships were reported (615) between the accumulation of labeled polar sterols and the levels of HMG-CoA reductase activity, and the incorporation of labeled hydrogen into NSL and "Chol" (characterized only by TLC). In other experiments, intragastric administration of ketoconazole (24 mg/kg) was reported to cause, at early time points (2-12 h), a decrease in hepatic HMG-CoA reductase, a decreased in vivo incorporation of 3 H 2 O into Chol, and an increase in the percentage of 3 H of NSL that was associated with polar sterols (679).…”