On the Influence of Cholesterol Feeding and of a Lipogenic Diet on the Cholesterogenesis in Rat Liver in vivo

Abstract The existence of a main regulation site(s) of the cholesterol synthesis located after the squalene formation is demonstrated by cholesterol feeding with labelled glucose, acetate, mevalonate as precursors and by measuring the incorporation rates into cholesterol, squalene, ubiquinones, and fatty acids in rat liver in vivo. By administration of labelled squalene in vivo it is shown that the isoprenic synthesis is inhibited between squalene and lanosterol but that other regulation site(s) after the lanosterol formation must exist. A regulation site of the cholesterogenesis in rat liver located after the squalene synthesis is also shown after a lipogenic diet administered during 5 days. The cholesterol synthesis is thus reduced to about one third of the control rats. Another regulating site controlling the utilization of acetylcoenzyme A for the synthesis of mevalonate is also shown to exist. No indication was obtained for a regulating influence located between mevalonate and squalene.