Ornithine decarboxylase and mucosal growth in response to feeding

The purpose of this study was to examine the role of ornithine decarboxylase (ODC) in the stimulation of the growth of gastrointestinal mucosa following feeding. Rats were divided into five groups: 1) fasted for 2 days, 2) fasted for 2 days and refed for 2 days, 3) fasted for 2 days and refed with the addition of 5% difluoromethylornithine (DFMO) to the drinking water, 4) normally fed, and 5) normally fed plus 5% DFMO in the drinking water. In general the results show a significant dissociation between ODC activity and growth of gastrointestinal mucosa in response to feeding. In the gastric mucosa, growth was inhibited by fasting and DFMO and stimulated by feeding, but there were no significant changes in ODC activity in any of the five groups. In the ileum ODC activity increased dramatically in refed rats and was essentially eliminated in rats fed DFMO. DFMO, however, had no effect on mucosal growth in fed rats and only prevented part of the trophic response to refeeding. The results in the colon were much the same as in the ileum, except that DFMO prevented even less of the trophic response to refeeding, despite total inhibition of ODC. These data suggest that polyamines necessary for growth of gastrointestinal mucosa following feeding are not supplied by the rapid activation of mucosal ornithine decarboxylase.