ABSTRACT
The ubiquitous tripeptide glutathione (GSH) is a critical component of the endogenous antioxidant defense system. Tissue GSH concentrations and redox status (GSH/GSSG) are genetically controlled, but it is unclear whether interactions between genetic background and diet affect GSH homeostasis. The current study tested the hypothesis that a high-fat diet regulates GSH homeostasis in a manner dependent on genetic background. At 4 months of age, female mice representing 3 obesity-prone inbred strains-C57BL/6J (B6), DBA/2J (D2), and AKR/J (AKR)-were randomly assigned to consume a control (10% energy from fat) or high-fat (62% energy from fat) diet for 10 weeks (n=5/diet per strain). Tissue GSH levels, GSSG levels, and GSH/GSSG were quantified, and hepatic expression of GSH-related enzymes was evaluated by quantitative reverse transcription polymerase chain reaction. The high-fat diet caused a decrease in hepatic GSH/GSSG in D2 mice. In contrast, B6 mice exhibited a decrease in GSSG levels in the liver and kidney, as well as a resultant increase in renal GSH/GSSG. AKR mice also exhibited increased renal GSH/GSSG on a high-fat diet. Finally, the high-fat diet induced a unique gene expression response in D2 mice compared with B6 and AKR. The D2 response was characterized by up-regulation of glutamate-cysteine ligase modifier subunit and down-regulation of glutathione reductase, whereas the B6 and AKR responses were characterized by up-regulation of glutathione peroxidase 1. Two-way analysis of variance analyses confirmed several diet-strain interactions within the GSH system, and linear regression models highlighted relationships between body mass and GSH outcomes as well. Overall, our data indicate that dietary fat regulates the GSH system in a strain-dependent manner.
Subject(s)
Diet, High-Fat/adverse effects , Dietary Fats/adverse effects , Gene-Environment Interaction , Glutathione/metabolism , Obesity/genetics , Phenotype , Animals , Body Weight , Dietary Fats/administration & dosage , Down-Regulation , Female , Glutamate-Cysteine Ligase/metabolism , Glutathione Disulfide/metabolism , Glutathione Peroxidase/metabolism , Glutathione Reductase/metabolism , Homeostasis , Kidney/metabolism , Liver/metabolism , Mice, Inbred AKR , Mice, Inbred C57BL , Mice, Inbred DBA , Mice, Obese , Obesity/etiology , Obesity/metabolism , Random Allocation , Reverse Transcriptase Polymerase Chain Reaction , Up-Regulation , Glutathione Peroxidase GPX1ABSTRACT
Anthocyanins are a class of phytochemicals that have generated considerable interest due to their reported health benefits. It has been proposed that commonly consumed anthocyanins, such as cyandin-3-O-ß-glucoside (C3G), confer cellular protection by stimulating biosynthesis of glutathione (GSH), an endogenous antioxidant. Currently, it is unknown whether the health effects of dietary anthocyanins are genetically determined. We therefore tested the hypothesis that anthocyanin-induced alterations in GSH homeostasis vary by genetic background. Mice representing five genetically diverse inbred strains (A/J, 129S1/SvImJ, CAST/EiJ, C57BL/6J, and NOD/ShiLtJ) were assigned to a control or 100mg/kg C3G diet (n=5/diet/strain) for six weeks. GSH and GSSG levels were quantified in liver, kidney, heart, pancreas, and brain samples using HPLC. The C3G diet promoted an increase in renal GSH concentrations, hepatic GSH/GSSG, and cardiac GSH/GSSG in CAST/EiJ mice. C3G treatment also induced an increase in pancreatic GSH/GSSG in C57BL/6J mice. In contrast, C3G did not affect GSH homeostasis in NOD/ShiLtJ mice. Surprisingly, the C3G-diet caused a decrease in hepatic GSH/GSSG in A/J and 129S1/SvImJ mice compared to controls; C3G-treated 129S1/SvImJ mice also exhibited lower total glutathione in the heart. Overall, we discovered that C3G modulates the GSH system in a strain- and tissue-specific manner. To our knowledge, this study is the first to show that the redox effects of anthocyanins are determined by genetic background.
