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Precocious and reversible expression of sucrase-isomaltase unrelated to intestinal cell turnover
E Nsi-Emvo1, C Foltzer-Jourdainne, F Raul
1Institut National de la Santé et de la Recherche Médicale, Université Louis Pasteur, Strasbourg, France.
Insights
Starvation in young rats triggers early intestinal sucrase-isomaltase (SI) production. Refeeding normalizes SI levels, with previously induced cells continuing production while new cells do not.
Area of Science:
- Gastroenterology
- Developmental Biology
- Molecular Biology
Background:
- Intestinal disaccharidase development is crucial for nutrient absorption.
- The regulation of sucrase-isomaltase (SI) during early life stages is not fully understood.
Purpose of the Study:
- To investigate the impact of starvation and refeeding on intestinal sucrase-isomaltase (SI) expression in preweaned rats.
Main Methods:
- Analysis of SI activity and mRNA levels.
- Immunostaining for SI localization.
- Measurement of other enzyme activities (alkaline phosphatase, aminopeptidase, lactase).
- Assessment of c-fos protooncogene expression and cell proliferation.
Main Results:
- Starvation induced precocious SI activity and mRNA expression, localized to basal villus cells.
- Refeeding decreased SI activity and mRNA to control levels, with newly formed cells not synthesizing SI.
- Starvation-induced SI expression occurred without increased cell proliferation, preceded by c-fos expression.
- SI expression patterns correlated with serum glucocorticoid levels.
Conclusions:
- Starvation can prematurely induce SI expression in developing rat intestines.
- Glucocorticoids and c-fos may play roles in mediating starvation-induced SI expression.
- SI regulation during starvation and refeeding involves distinct cellular responses compared to normal development.
Abstract:
The effect of starvation and refeeding on the developmental pattern of intestinal sucrase-isomaltase (SI) was analyzed in preweaned rats. Starvation at postnatal day 12 caused a precocious expression of SI activity and mRNA. Alkaline phosphatase activity was slightly reduced, and no significant change was observed for aminopeptidase and lactase activities. Immunostaining showed that SI molecules appear in cells at the base of the villus. Sucrase expression was further increased by prolonged food deprivation, whereas enzyme activity as well as the amount of SI mRNA dropped to reach the low level found in control sucklings when 48 h-starved pups were refed by returning them to their dams. During the refeeding period, the enterocytes that were committed to produce SI by starvation continued to express the enzyme while migrating up the villi. However, the new epithelial cells arising from the crypts no longer synthesized the disaccharidase. The starvation-evoked appearance of SI was preceded by a transient burst of expression of the protooncogene c-fos, an event that may be correlated to the ontogenic rise of c-fos mRNA observed before weaning. However, in contrast to the normal weaning condition, SI induction by starvation occurred without obvious increase of epithelial cell proliferation and turnover. During the starvation and refeeding period, patterns of sucrase activity and SI mRNA paralleled the serum level of glucocorticoids.(ABSTRACT TRUNCATED AT 250 WORDS)