Polyamines and intestinal growth: Absolute requirement for ODC activity in adaptation during lactation

Ornithine decarboxylase (ODC), through the regulation of polyamine biosynthesis, is important in cell proliferation and differentiation. We followed intestinal mucosal ODC activity in lactating Lewis rats and correlated the ODC levels with the characteristic small intestinal adaptive changes accompanying lactation. During the first 14 days of lactation, mucosal ODC activity increased, with the maximal increase on day 5 corresponding to the time of maximal morphological intestinal adaptation. In animals given the specific inhibitor of ODC, α-difluoromethylornithine (DFMO), intestinal mucosal ODC activity was inhibited, and intestinal adaptation was suppressed, with marked diminution of the adaptive increase in mucosal weight and thickness especially in crypt depth. Our results suggest that ODC activity plays an essential role in mucosal hyperplasia during the intestinal adaptation accompanying lactation, possibly through the stimulation of crypt cell proliferation.