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Phosphoenolpyruvate carboxykinase in the small intestine of developing rodents
Insights
Neonatal rats and mice exhibit high intestinal phosphoenolpyruvate carboxykinase activity. This activity declines post-weaning, suggesting a role for gluconeogenesis in the neonatal gut.
Area of Science:
- Biochemistry
- Developmental Biology
- Gastroenterology
Background:
- Phosphoenolpyruvate carboxykinase (PEPCK) is a key gluconeogenic enzyme.
- Intestinal gluconeogenesis is important for maintaining glucose homeostasis, especially during fasting.
- Little is known about PEPCK activity and its regulation in the developing gastrointestinal tract.
Purpose of the Study:
- To investigate the activity and developmental changes of phosphoenolpyruvate carboxykinase (PEPCK) in the small intestine of rats and mice.
- To explore the potential role of gluconeogenesis in the neonatal intestinal mucosa.
Main Methods:
- Measurement of phosphoenolpyruvate carboxykinase (PEPCK) activity in rat and mouse intestinal tissue.
- Analysis of PEPCK activity at different ages (suckling vs. weaned).
- Assessment of the effects of diet (high-fat) and starvation on intestinal PEPCK activity.
Main Results:
- High PEPCK activity was observed in the small intestine of suckling rats, decreasing significantly at weaning.
- Intestinal PEPCK activity was higher in the proximal than distal small intestine of suckling rats.
- In weaned rats, high-fat diet or starvation did not elevate low intestinal PEPCK activity.
- Suckling mice also showed high intestinal PEPCK activity, which increased with starvation but not with diet.
Conclusions:
- The neonatal rat small intestine exhibits significant PEPCK activity, suggesting a potential role for intestinal gluconeogenesis during this period.
- Dietary factors and starvation differentially regulate intestinal PEPCK activity in suckling and weaned rodents.
- Fructose-diphosphatase presence further supports the hypothesis of neonatal intestinal gluconeogenesis.
Abstract:
Phosphoenolpyruvate carboxykinase activity was found to be high in the mucosa of the small intestine of suckling rats. Activity was higher proximally than distally and decreased to very low values at weaning. After weaning, feeding a high fat diet or starvation did not result in elevation of the low intestinal activity in rats. However, in mice, who also showed high activity in the suckling period, starvation, but not diet, did cause a rise. Since fructose-diphosphatase was also found in the intestinal mucosa of suckling rats, it is suggested that gluconeogenesis may occur in this tissue in the neonatal period.