Effect of Dietary Lipid on Various Liver Enzymes and on in vivo Removal of 3,4-Dimethoxyphenylethylamine, 3,4-Dihydroxyphenylalanine and 5-Hydroxytryptophan in Rats

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Abstract
Feeding various dietary lipids to rats resulted in a 10-fold range in liver glucose-6-phosphate dehydrogenase activities. Highest rates were observed in rats fed beef fat or low levels of corn oil, intermediate activities were found in corn oil-fed rats, and lowest activities in animals fed menhaden or linseed oils. Similar but lesser differences in NADP-linked malic enzyme activities were also observed. These dietary lipid effects were related to the fatty acid composition of the lipid ingested and not to the dietary level of total lipid. Isocitric dehydrogenase (NADP-linked) and malic and lactic dehydrogenases (NAD-linked) were not affected by the dietary lipid. Liver tyrosine aminotransferase activities were lower in rats fed linseed or menhaden oils, in comparison with animals fed low polyunsaturated fatty acid-containing diets. In vivo utilization of injected dimethoxyphenylethylamine in rat liver was more rapid in animals fed high polyunsaturated fatty acid-containing diets, in comparison with rats fed 0.5% corn oil, 7% beef fat or 6.7% beef fat + 0.3% corn oil. No differences were found in the in vivo decarboxylation of dl-DOPA or dl-HTP regardless of the dietary lipid or the dose level of either amine precursor.