Morphological changes in hepatocytes of rats deprived of dietary nucleotides.

The aim of the present study was to investigate the influence of dietary nucleotides on liver morphology. Adult rats were fed for 21 d on a nucleotide-containing diet or the same diet free of nucleotides. Liver sections were examined by light and transmission electron microscopy, as well as for nucleic acid and protein contents. Morphometric analysis was performed for different variables. Deprivation of dietary nucleotides resulted in a reduction in hepatocyte nuclear and nucleolar areas as well as in nuclear chromatin condensation. In addition, the rough endoplasmic reticulum was reduced, as were ribosome association and abundance, whereas fat accumulated. These findings portray dietary nucleotides as required nutrients for the liver under normal physiological conditions and suggest that an inadequate supply of nucleotides for a certain period of time has transient negative effects on liver ultrastructure and function.

Deprivation of dietary nucleotides decreases protein synthesis in the liver and small intestine in rats.

BACKGROUND & AIMS: Dietary nucleotides are reported to influence the growth and functioning of the liver and small intestine. The aim of this study was to examine the mechanism by which nucleotides exert their effects in these tissues by assessing protein synthesis activity and related parameters in the presence or absence of dietary nucleotides. METHODS: Rats were fed a purified diet with or without nucleotides for 10 days. Fractional protein synthesis rate, RNA and DNA concentrations, polysome size distribution, and number of ribosomes were assessed. RESULTS: Fractional protein synthesis rates of the liver and small intestine were lower in the nucleotide-deprived group than in the control group. In the liver, RNA concentration was also lower in the nucleotide-deprived group, but values in the small intestine were similar in the two groups. In the liver, deprivation of nucleotides resulted in a reduction in the number of ribosomes and in polysome breakdown. Protein and DNA concentrations did not vary in the liver; however, the concentration of DNA was lower in the small intestine of the nucleotide-deprived group than in the control group. CONCLUSIONS: Dietary nucleotides can modulate protein synthesis in the liver and small intestine as a result of tissue-specific nucleic acid changes.

Deprivation of dietary nucleotides results in a transient decrease in acid-soluble nucleotides and RNA concentration in rat liver.

This study examines the contribution of dietary nucleotides to liver nucleotide pools in rats. Liver acid-soluble nucleotides, DNA and RNA concentrations were monitored in two groups of rats fed either a diet supplemented with nucleotides or a diet free of nucleotides for 3 wk. Significantly lower concentrations of ATP, ADP, GTP and CDP as well as of RNA were found after 1 wk in the rats fed a nucleotide-free diet compared with those fed the nucleotide-supplemented diet; concentrations remained lower after 2 wk except for ATP and ADP. No changes over time were observed in the rats fed the nucleotide-supplemented diet. Between wk 2 and 3 an increase in both acid-soluble nucleotides and RNA was observed in the rats fed the nucleotide-free diet, reaching the values found in the rats fed the nucleotide-supplemented diet. These findings, which indicate that dietary nucleotides are utilized at least in part by the liver to maintain the cell nucleotide pools and that diets devoid of nucleotides affect hepatic nucleotide metabolism and RNA, support the hypothesis that liver nucleotide metabolism is modulated by the availability of dietary nucleotides.