Peroxisomal Fatty Acid Research Articles

The Effect of Dehydroepiandrosterone Acetate on Liver Peroxisomal Enzyme Activities of Male and Female Rats

The present study is a follow-up to the report that dehydroeplandrosterone (DHEA) acetate treatment in rats stimulated metabolic heat production and suppressed serum triglycerides, adiposity and weight gain without affecting food intake. Activities of peroxisomal fatty acyl-coenzyme (CoA) oxidase and catalase as well as mitochondrial citrate synthase were assayed in liver tissue of 24 young adult male and female Wistar rats fed a nonpurified diet containing 0.6% DHEA (6 g/kg) for 6 wk. DHEA-treated animals gained less weight but had heavier liver weights than did the controls. Hepatic activity of fatty acyl-CoA oxidase of the experimental male and female animal was 1058 and 946% higher, respectively, than that of the controls. For catalase activity, only the female groups were different (30%). Activity of citrate synthase was not affected by DHEA. These data support the hypothesis that the inhibitory effect of DHEA on energy storage as fat is mediated, at least in part, by increased β-oxidation of fatty acids in peroxisomes. The peroxisomal β-oxidation pathway is uncoupled from oxidative phosphorylation; electrons are transferred directly to molecular O2 because of cycling of NAD/NADH resulting in the expenditure of chemical energy as heat.

Peroxisomal fatty acid β‐oxidation in human skin fibroblasts: X‐linked adrenoleukodystrophy, a peroxisomal very long chain fatty acyl‐CoA synthetase deficiency?

Peroxisomal fatty acid β‐oxidation in human skin fibroblasts: X‐linked adrenoleukodystrophy, a peroxisomal very long chain fatty acyl‐CoA synthetase deficiency?

Myocardial H2O2 production in the unanaesthetized rat. Influence of fasting, myocardial load and inhibition of superoxide dismutase and monoamine oxidase.

Myocardial H2O2 production was studied by means of the in vivo administration of aminotriazole (AT), which inactivates the catalase-H2O2 complex compound I. Measurements of the residual catalase activity in male and female rats indicate that beta-oxidation of fatty acids in peroxisomes does not contribute in a substantial way to energy production in response to fasting or to an increased myocardial load, despite previous data on peroxisomes in myocardium. Superoxide dismutase (SOD) inhibition by diethyldithiocarbamate demonstrates that SOD participates in the production of H2O2 in physiological conditions. Such a role was not demonstrated for monoamine oxidase through inhibition by phenelzine.

Degradation of unsaturated fatty acids in peroxisomes. Existence of a 2,4-dienoyl-CoA reductase pathway.

1. There are two 2,4-dienoyl-CoA reductases (EC 1.3.1.-) (formerly called 4-enoyl-CoA reductase, Eur. J. Biochem. (1978) 91, 533-544) in rat liver, one in mitochondria and another one in peroxisomes. 2. Treatment of rats with clofibrate increases the activities of the 2,4-dienoyl-CoA reductases in both cell organelles. 3. Isolated peroxisomes metabolize 4-cis-decenoyl-CoA, a metabolite of linoleic acid, via the 2,4-dienoyl-CoA reductase pathway. 4. From these results it is concluded that peroxisomes have the enzymatic apparatus necessary for the degradation of unsaturated fatty acids.