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Developmental changes in the phospho(enol)pyruvate carboxykinase gene expression in small intestine and liver of
1Department of Biochemistry, School of Pharmacy, University of Barcelona, Spain.
Insights
Phospho(enol)pyruvate carboxykinase (PEPCK) is highly expressed in the small intestine of suckling rats, with levels peaking early after birth and declining significantly by weaning. This intestinal PEPCK expression differs from liver expression and is influenced by maternal milk intake.
Area of Science:
- Biochemistry
- Developmental Biology
- Molecular Biology
Background:
- Phospho(enol)pyruvate carboxykinase (PEPCK) is a key gluconeogenic enzyme.
- Its expression and role in the intestine, particularly during development, are not fully understood.
- Suckling rats exhibit unique metabolic adaptations compared to adults.
Purpose of the Study:
- To investigate the developmental expression pattern of PEPCK mRNA in the intestinal mucosa of rats.
- To compare intestinal PEPCK expression with that in the liver during postnatal development.
- To explore the influence of diet and weaning on intestinal PEPCK levels.
Main Methods:
- Quantitative analysis of PEPCK mRNA levels using techniques like Northern blotting or RT-PCR.
- Tissue-specific expression analysis in different parts of the gastrointestinal tract (small intestine, stomach, colon, cecum).
- Monitoring of mRNA levels at various postnatal ages and in response to early weaning.
Main Results:
- PEPCK mRNA is markedly expressed in the small intestine of suckling rats, absent in the stomach, colon, and cecum.
- Intestinal PEPCK mRNA levels are low at birth, peak between 3-9 days postpartum, and decline sharply by weaning.
- Early weaning at Day 18 significantly reduces intestinal PEPCK mRNA levels, suggesting milk's influence. Liver PEPCK mRNA shows a different developmental profile, remaining high in adults.
Conclusions:
- Intestinal PEPCK expression in rats is developmentally regulated and specific to the small intestine during the suckling period.
- Maternal milk plays a crucial role in maintaining high levels of intestinal PEPCK during early life.
- The distinct developmental patterns of PEPCK in the intestine and liver highlight tissue-specific metabolic regulation.
Abstract:
The cytosolic enzyme phospho(enol)pyruvate carboxykinase (PEPCK) is markedly expressed in the intestinal mucosa of suckling rats. The expression is located in the small intestine, but there is no expression in stomach, colon, or cecum. The expression changes with age. The mRNA levels at birth are very low, increase after the first lactation, reach maximum levels between 3 and 9 days after birth, and then decrease smoothly. At weaning, when animals begin to feed on a solid chow diet, the expression falls to adult levels, which are hardly detectable. Mother's milk may influence the intestinal expression, since in rats weaned at Day 18, 3 days before normal weaning, the mRNA levels decreased dramatically. mRNA levels for PEPCK in liver present a rather different developmental pattern from that of intestine, remaining high at weaning and in adult rats. On the ninth day after birth, the mRNA levels are the same in intestine and liver.