Effects of Nonpurified and Choline Supplemented or Nonsupplemented Purified Diets on Hepatic Steatosis and Methionine Metabolism in C3H Mice.

BACKGROUND: Previous studies indicated that nonpurified and purified commercially available control murine diets have different metabolic effects with potential consequences on hepatic methionine metabolism and liver histology. METHODS: We compared the metabolic and histological effects of commercial nonpurified (13% calories from fat; 57% calories from carbohydrates with 38 grams/kg of sucrose) and purified control diets (12% calories from fat; 69% calories from carbohydrates with ∼500 grams/kg of sucrose) with or without choline supplementation administered to C3H mice with normal lipid and methionine metabolism. Diets were started 2 weeks before mating, continued through pregnancy and lactation, and continued in offspring until 24 weeks of age when we collected plasma and liver tissue to study methionine and lipid metabolism. RESULTS: Compared to mice fed nonpurified diets, the liver/body weight ratio was significantly higher in mice fed either purified diet, which was associated with hepatic steatosis and inflammation. Plasma alanine aminotransferase levels were higher in mice receiving the purified diets. The hepatic S-adenosylmethionine (SAM)/S-adenosylhomocysteine (SAH) ratio was higher in female mice fed purified compared to nonpurified diet (4.6 ± 2 vs. 2.8 ± 1.9; P < 0.05). Choline supplementation was associated with improvement of some parameters of lipid and methionine metabolism in mice fed purified diets. CONCLUSIONS: Standard nonpurified and purified diets have significantly different effects on development of steatosis in control mice. These findings can help in development of animal models of fatty liver and in choosing appropriate laboratory control diets for control animals.

Wilson Disease: Epigenetic effects of choline supplementation on phenotype and clinical course in a mouse model.

Wilson disease (WD), a genetic disorder affecting copper transport, is characterized by hepatic and neurological manifestations with variable and often unpredictable presentation. Global DNA methylation in liver was previously modified by dietary choline in tx-j mice, a spontaneous mutant model of WD. We therefore hypothesized that the WD phenotype and hepatic gene expression of tx-j offspring could be modified by maternal methyl supplementation during pregnancy. In an initial experiment, female tx-j mice or wild type mice were fed control or choline-supplemented diets 2 weeks prior to mating through embryonic day 17. Transcriptomic analysis (RNA-seq) on embryonic livers revealed tx-j-specific differences in genes related to oxidative phosphorylation, mitochondrial dysfunction, and the neurological disorders Huntington's disease and Alzheimer disease. Maternal choline supplementation restored the transcript levels of a subset of genes to wild type levels. In a separate experiment, a group of tx-j offspring continued to receive choline-supplemented or control diets, with or without the copper chelator penicillamine (PCA) for 12 weeks until 24 weeks of age. Combined choline supplementation and PCA treatment of 24-week-old tx-j mice was associated with increased liver transcript levels of methionine metabolism and oxidative phosphorylation-related genes. Sex differences in gene expression within each treatment group were also observed. These results demonstrate that the transcriptional changes in oxidative phosphorylation and methionine metabolism genes in WD that originate during fetal life are, in part, prevented by prenatal maternal choline supplementation, a finding with potential relevance to preventive treatments of WD.