Metabolic aspects of “orotic acid fatty liver”

Effects of Fatty Liver Induced by Excess Orotic Acid on B-Group Vitamin Concentrations of Liver, Blood, and Urine in Rats

Fatty liver is caused when rats are given orotic acid of the pyrimidine base in large quantities. The lack of B-group vitamins suppresses the biosynthesis of fatty acids. We investigated how orotic acid-induced fatty liver affects the concentrations of liver, blood, and urine B-group vitamins in rats. The vitamin B6 and B12 concentrations of liver, blood, and urine were not affected by orotic acid-induced fatty liver. Vitamin B2 was measured only in the urine, but was unchanged. The liver, blood, and urine concentrations of niacin and its metabolites fell dramatically. Niacin and its metabolites in the liver, blood, and urine were affected as expected. Although the concentrations of vitamin B1, pantothenic acid, folate, and biotin in liver and blood were decreased by orotic acid-induced fatty liver, these urinary excretion amounts showed a specific pattern toward increase. Generally, as for the typical urinary excretion of B-group vitamins, these are excreted when the body is saturated. However, the ability to sustain vitamin B1, pantothenic acid, folate, and biotin decreased in fatty liver, which is hypothesized as a specific phenomenon. This metabolic response might occur to prevent an abnormally increased biosynthesis of fatty acids by orotic acid.

The influence of vitamin A status on the response of chickens to aflatoxin B1 and changes in liver lipid metabolism associated with aflatoxicosis

1 A series of experiments were conducted to investigate the effects of dietary retinol status on chickens ingesting aflatoxin B1. The effects of dietary supplementation with biotin and alpha-tocopherol were also examined. 2. Aflatoxin B1 levels greater than 1 mg/kg diet had a detrimental effect on 'liveability', body-weight gain, food intake and food conversion efficiency. When fed for more than 2 weeks aflatoxin increased relative liver weight and liver lipid concentration. These effects were less pronounced with avitaminotic A chickens. 3. A synergistic effect on hydropericardium development was observed between aflatoxin B1 and retinol. This effect was not observed when the dietary level of alpha-tocopherol was increased tenfold. 4. The specific activities of certain hepatic lipogenic and amino acid-metabolizing enzymes were influenced by aflatoxin ingestion. A reduction in lipogenic enzyme activity was observed before a reduction in the activities of amino acid-metabolizing enzymes. 5. Liver fatty acid composition was significantly influenced by aflatoxin B1. The extent of these changes was reduced by the inclusion of additional dietary biotin.