title: On the mechanism of stimulation of peroxisomal beta-oxidation in rat heart by partially hydrogenated fish oil.
abstract: By feeding rats a diet containing 20% (w/w) partially hydrogenated fish oil (PHFO), an apparent 6.3-fold increase in the cyanide insensitive palmitoyl-CoA-dependent NAD+ reduction was observed for the heart peroxisomal fractions. This finding was confirmed by a 7.6-fold and 7.9-fold increase in the specific activity of fatty acyl-CoA oxidase, with palmitoyl-CoA and erucoyl-CoA as the substrates, respectively. Immunoblots after SDS-PAGE of rat heart peroxisomal fractions revealed a 12-fold increase in the 52 kDa fatty acyl-CoA oxidase (FAO) subunit for PHFO-fed rats, whereas the 72 kDa subunit of FAO and several other peroxisomal proteins (including the trifunctional enzyme delta 3,delta 2-enoyl-CoA isomerase, 2-enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase) increased only 2- to 3-fold. The increase in the 52 kDa subunit was markedly higher than the increase in the steady-state mRNA level of FAO (2.0-fold), and is most likely caused by a rather selective stabilization of the 52 kDa FAO subunit. Interestingly, PHFO feeding caused a larger increase in fatty acyl-CoA oxidase and catalase activities than did clofibrate in the heart. The opposite was the case in the liver, especially for fatty acyl-CoA oxidase. Rats fed a semisynthetic diet containing 6% (w/w) erucic acid (C22:1(n - 9), cis) or brassidic acid (C22:1(n - 9), trans) revealed a 5-fold and 3-fold increase vs. the control (pellet fed) rats in heart FAO activity, respectively, as well as a proportional and selective increase in the specific content of 52 kDa FAO subunit. Thus, the relatively high content of C22 monoene fatty acids appears to be one of the main factors responsible for the increase in rat heart peroxisomal FAO activity during PHFO feeding. However, the PHFO diet increased the heart peroxisomal FAO activity more than diets containing a similar amount of C22:1 in the form of erucic or brassidic acid, and additional compounds of lipid or a more xenobiotic nature may also play a role. SDS-PAGE electrophoresis of highly purified rat liver peroxisomes revealed that the specific content of polypeptides with mobilities corresponding to that of the beta-oxidation enzyme system, increased by a factor of < 2 as a result of feeding the PHFO diet. The 3.1-fold increase in cyanide insensitive palmitoyl-CoA-dependent NAD+ reduction was comparable to the increase (4.1-fold) in the acyl-CoA oxidase activity.(ABSTRACT TRUNCATED AT 400 WORDS)
authors.affiliation: Department of Biochemistry and Molecular Biology, University of Bergen, Norway.
authors.forename: J
authors.initials: J
authors.lastname: Kvannes
authors.forename: T S
authors.initials: TS
authors.lastname: Eikhom
authors.forename: T
authors.initials: T
authors.lastname: Flatmark
mesh_terms: D015094:3-Hydroxyacyl CoA Dehydrogenases / Q000096:biosynthesis; D042962:Acyl-CoA Oxidase; D000818:Animals; D000906:Antibodies / Q000276:immunology; D002374:Catalase / Q000096:biosynthesis; D002994:Clofibrate / Q000494:pharmacology; D004042:Dietary Fats, Unsaturated / Q000494:pharmacology*; D004746:Enoyl-CoA Hydratase / Q000096:biosynthesis; D004790:Enzyme Induction; D005231:Fatty Acids, Unsaturated / Q000494:pharmacology; D005395:Fish Oils / Q000494:pharmacology*; D006321:Heart / Q000187:drug effects*; D015151:Immunoblotting; D007535:Isomerases / Q000096:biosynthesis; D008099:Liver / Q000187:drug effects / Q000201:enzymology; D008297:Male; D008830:Microbodies / Q000187:drug effects* / Q000378:metabolism; D009097:Multienzyme Complexes / Q000096:biosynthesis; D010084:Oxidation-Reduction / Q000187:drug effects; D010088:Oxidoreductases / Q000096:biosynthesis* / Q000737:chemistry / Q000276:immunology; D063994:Peroxisomal Bifunctional Enzyme; D051381:Rats; D017208:Rats, Wistar
chemical_list: D000906:Antibodies; D004042:Dietary Fats, Unsaturated; D005231:Fatty Acids, Unsaturated; D005395:Fish Oils; D009097:Multienzyme Complexes; D010088:Oxidoreductases; D015094:3-Hydroxyacyl CoA Dehydrogenases; D002374:Catalase; D042962:Acyl-CoA Oxidase; D004746:Enoyl-CoA Hydratase; D063994:Peroxisomal Bifunctional Enzyme; D007535:Isomerases; D002994:Clofibrate