title: Differential effects of geometrical isomers of octadecadienoic acids on ketogenesis and lipid secretion in the livers from rats fed a cholesterol-enriched diet.
abstract: The effect of cis,cis (cc)- and trans,trans (tt)-9,12-octadecadienoic (18:2) acids on ketogenesis and lipid secretion was compared in isolated perfused livers from cholesterol-fed rats. The hepatic uptake of 18:2 acids was comparable in both isomers. The livers perfused with cc-18:2 acid in comparison with those perfused without fatty acid substrate produced approximately 4-fold more ketone bodies accompanying the rise of the beta-hydroxybutyrate:acetoacetate ratio, while the tt-acid isomer further increased these parameters. The hepatic secretion rates of triglyceride and phospholipid as well as cholesterol were all elevated on perfusing the cc-18:2 acid as compared to without fatty acid. In contrast, the rates observed with the tt-18:2 acid isomer except for phospholipid were intermediate, indicating a reciprocal response in ketogenesis and lipid secretion by the trans isomer. The rate of incorporation of trans-fatty acid into perfusate triglyceride and cholesterol ester were lower than cis-acid, but vice versa into perfusate phospholipids. On the other hand, the effects of trans-fatty acid on the concentration and composition of hepatic lipids were less clear. These results emphasize the differential effect of geometrical isomers of the 18:2 acids on oxidation and esterification even in the livers containing a high level of cholesterol.
mesh_terms: D020155:3-Hydroxybutyric Acid; D000090:Acetoacetates / Q000032:analysis; D000818:Animals; D002784:Cholesterol / Q000032:analysis; D002788:Cholesterol Esters / Q000032:analysis; D002791:Cholesterol, Dietary / Q000494:pharmacology*; D005231:Fatty Acids, Unsaturated / Q000378:metabolism*; D006885:Hydroxybutyrates / Q000032:analysis; D007657:Ketone Bodies / Q000096:biosynthesis*; D008055:Lipids / Q000032:analysis*; D008099:Liver / Q000737:chemistry / Q000187:drug effects*; D010743:Phospholipids / Q000032:analysis; D051381:Rats; D013237:Stereoisomerism; D014280:Triglycerides / Q000032:analysis
chemical_list: D000090:Acetoacetates; D002788:Cholesterol Esters; D002791:Cholesterol, Dietary; D005231:Fatty Acids, Unsaturated; D006885:Hydroxybutyrates; D007657:Ketone Bodies; D008055:Lipids; D010743:Phospholipids; D014280:Triglycerides; C027369:octadecadienoic acid; C016635:acetoacetic acid; D002784:Cholesterol; D020155:3-Hydroxybutyric Acid