In vivo cholesterol removal from liver microsomes induces changes in fatty acid desaturase activities.
Rats fed a 1% cholesterol and 0.5% cholate diet for 21 days were transferred to a sterol-free diet after variable periods of time. The effect of cholesterol removal on liver microsomal composition and fatty acid desaturases was studied. Some changes were already observed after 1 day. However, after 21 days of a sterol-free diet, the cholesterol content of liver microsomes decreased as well as that of phosphatidylcholine. So did the cholesterol/phospholipid ratio. Phosphatidylinositol, phosphatidylserine and sphingomyelin slightly increased along with time. The total fatty acid composition was altered by a decrease in monounsaturated acids and an increase in the saturated acids, palmitic and stearic acids. The arachidonic acid content rose. A similar pattern of change was found in the fatty acid composition of the main phospholipids: phosphatidylcholine and phosphatidylethanolamine. delta 9-Desaturase activity steadily decreased along with cholesterol removal, whereas delta 5- and delta 6-desaturase activities were enhanced towards the end of the removal period. The microsomal membrane became more 'fluid', according to the decrease of fluorescence anisotropy of the 1,6-diphenyl-1,3,5-hexatriene incorporated into the membrane.
Leikin
A I
AI
Instituto de Investigaciones Bioquimicas de La Plata, CONICET-UNLP Facultad de Cs. Médicas, Argentina.
Brenner
R R
RR
D000818:Animals; D002784:Cholesterol / Q000032:analysis / Q000502:physiology*; D002791:Cholesterol, Dietary / Q000494:pharmacology*; D019826:Cholic Acid; D002793:Cholic Acids / Q000494:pharmacology*; D044943:Fatty Acid Desaturases / Q000378:metabolism*; D007700:Kinetics; D008297:Male; D008862:Microsomes, Liver / Q000201:enzymology*; D010743:Phospholipids / Q000032:analysis; D051381:Rats; D011919:Rats, Inbred Strains; D012016:Reference Values
D002791:Cholesterol, Dietary; D002793:Cholic Acids; D010743:Phospholipids; D002784:Cholesterol; D044943:Fatty Acid Desaturases; D019826:Cholic Acid