BACKGROUND: Healthy human adults are able to hydrolyze dietary nucleic acids and nucleotides in the gastrointestinal tract, thus facilitating absorption of the resulting nucleosides. However, little is directly known of the ability of infants to hydrolyze nucleic acids early in life. METHODS: Purified RNA (50, 100, 250, and 500 mg/L) in a suitable medium was exposed to jejunal explants of weaning piglets to determine if enzymes expressed by the explants were sufficient to hydrolyze the nucleic acid. Aliquots from the media were taken at time intervals, from 0 to 6 hours, and assayed for ribonucleoside content by high-performance liquid chromatography. RESULTS: The investigators found a significant increase of free ribonucleosides during the study period and for all RNA concentrations tested, thus suggesting that intestinal explants are able to hydrolyze RNA. The kinetics of nucleoside concentrations varied for each nucleoside. For example, inosine increased over the entire 6-hour period and adenosine increased for the first 2 hours, decreasing afterward. CONCLUSIONS: It is concluded that cells from the intestinal epithelium are capable of hydrolyzing RNA. These results suggest that RNA present in human milk is hydrolyzed in the intestinal tract of the breast-fed infant, thus providing an additional source of nucleosides. The results indicate that current supplementation of infant formulas with nucleotides should be reconsidered to take into account the contribution of RNA present in human milk to the pool of bioavailable nucleotides.
BACKGROUND: Healthy human adults are able to hydrolyze dietary nucleic acids and nucleotides in the gastrointestinal tract, thus facilitating absorption of the resulting nucleosides. However, little is directly known of the ability of infants to hydrolyze nucleic acids early in life. METHODS: Purified RNA (50, 100, 250, and 500 mg/L) in a suitable medium was exposed to jejunal explants of weaning piglets to determine if enzymes expressed by the explants were sufficient to hydrolyze the nucleic acid. Aliquots from the media were taken at time intervals, from 0 to 6 hours, and assayed for ribonucleoside content by high-performance liquid chromatography. RESULTS: The investigators found a significant increase of free ribonucleosides during the study period and for all RNA concentrations tested, thus suggesting that intestinal explants are able to hydrolyze RNA. The kinetics of nucleoside concentrations varied for each nucleoside. For example, inosine increased over the entire 6-hour period and adenosine increased for the first 2 hours, decreasing afterward. CONCLUSIONS: It is concluded that cells from the intestinal epithelium are capable of hydrolyzing RNA. These results suggest that RNA present in human milk is hydrolyzed in the intestinal tract of the breast-fed infant, thus providing an additional source of nucleosides. The results indicate that current supplementation of infant formulas with nucleotides should be reconsidered to take into account the contribution of RNA present in human milk to the pool of bioavailable nucleotides.