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Effect of exogenously administered polyamine on the structural maturation and enzyme ontogeny of the postnatal rat
Insights
Exogenous spermidine administration in young rats precociously altered intestinal development, affecting enzyme activity and morphology. This polyamine influences key developmental processes before weaning.
Area of Science:
- Developmental Biology
- Gastroenterology
- Molecular Biology
Background:
- Postnatal intestinal development involves complex changes in morphology and enzyme activity.
- Ornithine decarboxylase (ODC) and polyamine levels rise with mucosal growth preceding weaning.
Purpose of the Study:
- To investigate the impact of exogenous spermidine on the structural and functional differentiation of the developing rat intestine.
- To understand the role of polyamines in regulating intestinal maturation.
Main Methods:
- Rats were administered spermidine (6 mumol) for 1 or 3 days before postnatal day 10.
- Control groups included rats sacrificed at day 10 and day 49 (adult).
- Intestinal morphology, enzyme activities (N-acetyl-glucosaminidase, sucrase, lactase), and ODC activity were analyzed.
Main Results:
- Spermidine treatment led to a loss of endosomal complex and giant lysosomes in ileal and colonic absorptive cells.
- N-acetyl-glucosaminidase activity decreased to adult levels.
- Precocious increases in sucrase and NaK ATPase activities were observed, while lactase levels declined.
- Mucosal ODC activity increased following spermidine administration.
Conclusions:
- Exogenous spermidine accelerates intestinal maturation, inducing premature enzyme activity and altering cellular structures.
- Polyamines like spermidine play a significant role in regulating postnatal intestinal development and differentiation.
- These findings provide insights into the molecular mechanisms governing intestinal adaptation before weaning.
Abstract:
The factors regulating the developmental changes in intestinal morphology and enzyme activity during the postnatal period are incompletely understood. Increased ornithine decarboxylase (ODC) and polyamine levels occur in association with increased mucosal growth seen just prior to weaning. The present work examines the effects of the polyamine spermidine, administered exogenously during early postnatal development in the rat, on structural and functional differentiation of the intestine. Young rats were fed 6 mumol of spermidine for either 1 day (P1) or 3 days (P3) prior to sacrifice on postnatal day 10. Control littermates were sacrificed at day 10 (C10) or at day 49 (C49) (postweanling [adult] reference). A loss of most of the well-developed characteristic endosomal complex and supranuclear giant lysosome was observed in the absorptive cells of the ileum and proximal colon in the spermidine-treated groups and was accompanied by a decline in N-acetyl-glucosaminidase activity to adult levels. A precocious appearance of sucrase and NaK ATPase activities was observed in the P1 group and these activities attained adult levels in the P3 group. This premature appearance of sucrase and NaK ATPase activities was associated with a decline in lactase levels. The exogenous administration of spermidine also elicited an increase in mucosal ODC activity.