The influence of methionine, selenomethionine, and vitamin E on liver metabolic pathways and steatosis in high-cholesterol fed rabbits

Identification of Plasmatic Biomarkers of Foie Gras Qualities in Duck by Metabolomics

The foie gras is an emblematic product of French gastronomy composed of waterfowl fatty liver. The organoleptic qualities of this product depend on the liver characteristics such as liver weight (LW) and technological yield (TY) at cooking. One of the main issues for producers is to classify the foie gras with high or low technological quality before cooking them. Thus the study aims at identifying biomarkers of these characteristics with non-invasive biomarkers in duck. ¹H-NMR (nuclear magnetic resonance of the proton) analyses were performed on plasma of male mule ducks at different time points during the overfeeding period to obtain a large range of liver characteristics so as to identify plasmatic biomarkers of foie gras. We used two methods, one based on bucket data from the ¹H-NMR spectra and another one based on the fingerprints of several metabolites. PLS analyses and Linear models were performed to identify biomarkers. We identified 18 biomarkers of liver weight and 15 biomarkers of technological yield. As these two quality parameters were strongly correlated (−0.82), 13 biomarkers were common. The lactate was the most important biomarker, the other were mainly amino acids. Contrary to the amino acids, the lactate increased with the liver weight and decreased with the technological yield. We also identified 5 biomarkers specific to LW (3 carbohydrates: glucuronic acid, mannose, sorbitol and 2 amino acids: glutamic acid and methionine) that were negatively correlated to liver weight. It was of main interest to identify 2 biomarkers specific to the technological yield. Contrary to the isovaleric acid, the valine was negatively correlated to the technological yield.

Attenuation of high cholesterol-induced oxidative stress in rabbit liver by thymoquinone

BACKGROUND/AIMS

This study examines the modifying effects of thymoquinone (TQ), an agent with antioxidant and hypolipidemic properties, on reactive oxygen species, antioxidant activity, and steatosis in livers of hyperlipidemic rabbit.

METHODS

Oxidative stress was induced in New Zealand White rabbit by a high-cholesterol diet for 8 weeks. Four groups of six animals each were divided into a control group; a high cholesterol group (received 1% cholesterol diet); a high cholesterol/low TQ group (received 1% cholesterol diet plus TQ 10 mg/kg/day), and a high cholesterol/high TQ (20 mg/kg/day) group. Blood samples were taken at the end of the study and examined for fasting serum glucose, insulin, and aminotransaminases. Hepatic tissue samples were examined for malondialdehyde, protein carbonyls, antioxidant enzymes, and steatosis.

RESULTS

There was severe hepatic steatosis and elevated serum alanine aminotransferase in the high cholesterol group (group II) but not in the high cholesterol and low or high TQ groups (groups III, IV). The hepatic reactive oxygen species activity in the high cholesterol group was significantly higher while the antioxidant enzymes were lower (P<0.05) when compared with the control (group I) or either of the high cholesterol and TQ groups.

CONCLUSION

TQ attenuates hepatic oxidative stress in fatty liver injury induced by high-cholesterol diet in rabbits.

Oral supplementation with L-aspartate and L-glutamate inhibits atherogenesis and fatty liver disease in cholesterol-fed rabbit

Previous studies have shown that dietary supplementation with L-aspartate and L-glutamate inhibits fatty streak initiation in cholesterol-fed rabbit. The present study investigates the role of dicarboxylic amino acids on the progression of fatty streaks and the development of fatty liver disease, which were caused in New Zealand White rabbits after a 0.5% w/w cholesterol diet for 7 weeks. A group of animals additionally received a combination of 12.5 mM L-aspartate and 12.5 mM L-glutamate per day through drinking water. Total cholesterol (TC), high-density lipoproteins cholesterol (HDLC), non-HDLC and triacylglycerol (TAG) concentrations were measured in plasma. Serum gamma-glutamyl transferase (gamma-GT), aspartate aminotransferase (AST) and alanine aminotransferase (ALT) activities were also determined. At the end of dietary intervention, animals were sacrificed. Aortic, hepatic and brain lesions were evaluated after staining with hematoxylin and eosin. Supplementation with dicarboxylic amino acids inhibited the progression of aortic intima thickness (P < 0.05) and the development of liver lesions (P < 0.05). TC, non-HDLC and TAG were similarly increased in both cholesterol-fed groups. Serum gamma-GT and AST activities elevated during the study in all cholesterol-fed animals but the elevation of gamma-GT was milder and significantly lower in rabbits treated with L-aspartate and L-glutamate (P < 0.05). ALT activity was not affected by cholesterol feeding. In conclusion, oral supplementation with L-aspartate and L-glutamate inhibits the progression of atherogenesis and the development of fatty liver disease in the animal model of cholesterol-fed rabbit. The beneficial effects of dicarboxylic amino acids reflect the limited elevation of serum gamma-GT activity.