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Pyruvate carboxylase, phosphate-dependent glutaminase and glutamate dehydrogenase in the developing rat small
1Department of Obstetrics, University of British Columbia, Vancouver, Canada.
Insights
Enzymatic activity in infant rat intestines changes significantly during weaning. Gluconeogenesis (glucose creation) appears to primarily use the oxaloacetate pathway, not the alpha-ketoglutarate route.
Area of Science:
- Biochemistry
- Developmental Biology
- Gastroenterology
Background:
- Infant intestinal metabolism undergoes significant shifts during the transition from milk-based to solid food diets.
- Understanding these metabolic adaptations is crucial for infant nutrition and gut health.
Purpose of the Study:
- To investigate the changes in key gluconeogenic enzyme activities in the small intestinal mucosa of infant rats during the weaning period.
- To elucidate the primary pathway utilized for gluconeogenesis in the infant intestinal mucosa.
Main Methods:
- Assay of glutaminase, glutamate dehydrogenase, and pyruvate carboxylase activities in the small intestinal mucosa.
- Comparison of enzyme activities between suckling and weaned infant rats.
Main Results:
- Glutaminase and glutamate dehydrogenase activities increased significantly at weaning.
- Pyruvate carboxylase activity was high in suckling rats and decreased to negligible levels post-weaning.
Conclusions:
- The observed enzyme activity patterns suggest that gluconeogenesis in the infant rat small intestine predominantly proceeds via the oxaloacetate pathway.
- These findings highlight a specific metabolic adaptation in the gut mucosa during the critical weaning phase.
Abstract:
The activities of glutaminase and glutamate dehydrogenase in the small intestinal mucosa of infant rats were found to increase at the time of weaning. Pyruvate carboxylase activity, on the other hand, was very high during the suckling period and decreased to negligible values at weaning. It is suggested that gluconeogenesis in the infant mucosa occurs primarily via oxaloacetate and not via alpha-ketoglutarate.