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Phosphatidylcholine synthesis in the developing small intestine
Insights
Phosphatidylcholine synthesis in rat intestines changes significantly after birth. Enzyme activities and oleic acid incorporation peak in young rats, with distinct patterns in the jejunum and ileum.
Area of Science:
- Biochemistry
- Developmental Biology
- Gastroenterology
Background:
- Phosphatidylcholine is a crucial phospholipid for cell membranes.
- Intestinal development involves significant changes in metabolic pathways.
Purpose of the Study:
- To investigate the developmental changes in phosphatidylcholine synthesis in the rat small intestine.
- To characterize the activity of key enzymes involved in phosphatidylcholine synthesis and substrate incorporation during different life stages.
Main Methods:
- Assessed cytidine diphosphocholine-1,2-diacylglycerocholine phosphotransferase (cholinephosphotransferase) and acyl-CoA-1-acyl-sn-glycerol-3-phosphocholine acyltransferase (lysophosphatidylcholine acyltransferase) activities.
- Measured the incorporation of [1-14C]oleic acid into phosphatidylcholine in jejunal and ileal tissues.
- Examined the effects of cortisone administration on these pathways in the postnatal jejunum.
Main Results:
- Cholinephosphotransferase activity increased postnatally, with distinct maturation timelines in the jejunum and ileum.
- Lysophosphatidylcholine acyltransferase activity showed a sharp decrease after birth in the jejunum, followed by a rise to adult levels.
- Oleic acid incorporation into phosphatidylcholine was significantly higher in 10-day-old rats compared to adults, particularly in the jejunum.
- Cortisone administration did not stimulate postnatal jejunal enzyme activities or oleic acid incorporation.
Conclusions:
- Rat small intestinal phosphatidylcholine synthesis undergoes dynamic developmental regulation.
- Enzyme activities and substrate incorporation exhibit distinct regional and temporal patterns during postnatal development.
- The postnatal jejunum shows heightened phosphatidylcholine synthesis capacity, which is not influenced by cortisone in vivo.
Abstract:
1. Phosphatidylcholine synthesis in the foetal, newborn and adult small intestine of rats was studied by determination of cytidine diphosphocholine-1,2-diacylglycerocholine phosphotransferase (cholinephosphotransferase) and acyl-CoA-1-acyl-sn-glycerol-3-phosphocholine acyltransferase (lysophosphatidylcholine acyltransferase) activities and the incorporation of [1-14C]oleic acid into phosphatidylcholine. 2. Cholinephosphotransferase activity was low in foetal jejunum and ileum, increased 3-4 fold in the ileum by 6 days of age and by 12 days in the jejunum. Jejunal activity remained constant throughout weaning; ileal activity gradually decreased to values 25% of that of the jejunum. 3. Lysophosphatidylcholine acyltransferase activity was high in foetal jejunum and ileum, decreased 70% immediately after birth in the jejunum and increased to adult values by 12 days of age. Ileal activity decreased by 20% after birth, but decreased more rapidly at weaning to 30% of the activity in jejunum. 4. Initial rates and steady-state incorporation of [1-14C]oleic acid into phosphatidylcholine by jejunal rings of 10 day-old rats exceeded that observed in jejunal rings from adult rats by 2-4-fold. 5. In the postnatal jejunum, neither cholinephosphotransferase and lysophosphatidylcholine acyltransferase activities nor oleic acid incorporation were stimulated by cortisone administration in vivo.