ESSENTIAL ROLE OF POLYAMINE BIOSYNTHESIS IN INTESTINAL GROWTH INDUCED BY EARLY WEANING

Abstract

87 Ornithine decarboxylase (ODC) is the first and rate-limiting enzyme in polyamine biosynthesis. Our previous study showed that early weaning induced intestinal ODC and cell proliteration, and that the induced ODC activity was the earliest cellular event observed. These findings provide no information whether ODC is required during early-weaning induced intestinal growth. Aim: To investigate the effect of DFMO (α-difluoromethylornithine, a specific inhibitor of ODC) on intestinal growth during early weaning. Methods: Suckling rats (15 day old) were divided into four groups (1) Unweaned control; (2) Early weaned; (3) Wean+DFMO (pups weaned precociously on day 15 and fed drinking water containing 2% DFMO); (4) DFMO (dam fed drinking water containing 3% DFMO while nursing pups). Rat pups from each group were killed on postnatal days 16 and 17. The jejunal mucosa was assayed for ODC and sucrase activities Results: The early weaned group showed the most significant increase in ODC activity on postnatal days 16 and 17. ODC activities were significantly suppressed by DFMO after early weaning. The jejunal sucrase activities showed a similar pattern as that of ODC. The sucrase activities of early weaned rats were significantly suppressed when pups received DFMO in drinking water. Our results demonstrated that DFMO effectively suppressed jejunal ODC activity induced by early weaning, and that sucrase activity induced by early weaning was also suppressed when DFMO was given. Conclusion: Our results suggest that ODC plays an essential role in intestinal precocious development induced by early weaning.