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Postnatal intestinal maturation in rats: alpha-aminoisobutyric acid loss during in vivo, perfusion by hypertonic
Insights
Young rats secrete more amino acids from their intestines than older rats, especially during diarrhea. This suggests increased intestinal permeability in infant animals puts them at risk of nutrient loss.
Area of Science:
- Gastroenterology
- Developmental Biology
- Physiology
Background:
- Intestinal permeability changes with age.
- Amino acid absorption is crucial for infant nutrition.
- Osmotic diarrhea can lead to significant nutrient loss.
Purpose of the Study:
- To investigate age-related differences in intestinal amino acid secretion.
- To determine the effect of hypertonic solutions on amino acid secretion in rats of different ages.
- To assess the risk of amino acid loss during osmotic diarrhea in infant animals.
Main Methods:
- In vivo single-pass perfusion technique was used.
- Net secretion of [14C]aminoisobutyric acid was measured.
- Experiments were conducted on suckling, weanling, and adolescent rats.
Main Results:
- Suckling rats showed significantly greater net secretion of [14C]aminoisobutyric acid compared to adolescent rats.
- Weanling rats exhibited intermediate secretion rates.
- Hypertonic solutions increased amino acid secretion in suckling rats but not in weanling or adolescent rats.
- The colon was identified as the primary site of amino acid secretion.
Conclusions:
- Intestinal epithelium in suckling rats is more permeable to amino acids than in adolescent rats.
- Infant animals are at risk of amino acid loss during osmotic diarrhea due to increased intestinal permeability.
- Age-dependent changes in intestinal permeability influence nutrient absorption and retention.
Abstract:
We investigated with an in vivo single pass perfusion technique net secretion of [14C]aminoisobutyric acid, a non-metabolizable amino acid, from the proximal, distal small intestinal segments and from the colon segments of suckling (14-15 day old), weanling (21-22 day old) and adolescent (42-43 day old) rats during perfusion with either isotonic (300 mOsm/Kg) or hypertonic (500 mOsm/Kg) solutions. During isotonic perfusion, net secretion of [14C]aminoisobutyric acid was significantly greater in all segments of the suckling rats compared to corresponding values in segments of the adolescent rats. Rates of net secretion of [14C]aminoisobutyric acid in all segments of the weanling rats were intermediate between corresponding mean values of the suckling and adolescent rats. When secretion of [14C]aminoisobutyric acid was compared between individual segments, the colon was the major site of secretion followed by the proximal and then the distal segments in all age groups. During perfusion with hypertonic solutions there was significant increase in net secretion of [14C]aminoisobutyric acid in all segments of the suckling rats compared to mean values with isotonic perfusion. In the weanling and adolescent rats, there were no significant differences in the rates of net secretion of [14C]aminoisobutyric acid with hypertonic perfusion. Our findings suggests greater permeability of the intestinal epithelium not only to water, electrolytes and minerals but also to amino acids in the suckling rats compared to adolescent rats. The implication is that during periods of osmotic diarrhea infant animals appear to be at risk of losing amino acids.(ABSTRACT TRUNCATED AT 250 WORDS)