Docosahexaenoic Acid-Induced Lipid Peroxidation and Urinary Excretion of Mercapturic Acid in Rats

Abstract

Summary We hypothesized a suppressive mechanism for dietary docosahexaenoic acid (DHA)-induced tissue lipid peroxidation in which the degradation products, especially aldehydic compounds, are conjugated with glutathione (GSH) through catalysis by glutathione S-transferases (GSTs), and then excreted into urine as mercapturic acids. Sprague-Dawley rats were fed a diet containing DHA (8.4 % of total energy) for 31 days. Lipid peroxides in the liver and kidney, liver GST and urinary excretion of mercapturic acid were measured. The lipid peroxide levels in the liver and kidney except the liver aldehydic compounds were higher, and the urinary excretion of mercapturic acid also tended to be higher in the DHA-fed rats although the activity of GST was not increased after DHA intake. We presume from our results that a proportion of the lipid peroxidation-derived aldehydic degradation products might be excreted into urine as mercapturic acid after intake of DHA, thus suppressing the accumulation of aldehydic products in tissues, particularly in the liver.

Effect of Docosahexaenoic Acid Ingestion on Temporal Change in Urinary Excretion of Mercapturic Acid in ODS Rats

“…In addition, the excretion on day 28 tended to be higher with DHA intake. This result on day 28 was similar to our previous report [ 27 ]. We have reported the gene expression of dietary DHA-induced multidrug resistance-associated protein 3 in the liver [ 40 ], which could mediate the transport of reactive aldehydes conjugated with GSH into blood stream from the liver.…”

“…In this study, therefore, we focused in particular on detoxification and/or excretion mechanisms for suppressing the accumulation of lipid peroxides and their degradation products induced after DHA intake. Our previous study showed that DHA ingestion elevated the urinary excretion of mercapturic acids on day 28 in Sprague-Dawley rats [ 27 ]. Hence, we measured here the temporal change in the urinary excretion of mercapturic acids in AsA-requiring Osteogenic Disorder Shionogi/Shi-od/od (ODS) rats after DHA intake.…”