ROLE OF POLYAMINES IN THE EARLY ADAPTIVE RESPONSE TO JEJUNECTOMY IN THE RAT - EFFECT OF DFMO ON THE ILEAL VILLUS - CRYPT AXIS

To study the role of the polyamines putrescine, spermidine and spermine and of the enzymes controlling their synthesis (ornithine decarboxylase; ODC) and degradation (diamine oxidase; DAO) along the villusxrypt axis at the crucial early stage of the ileal adaptive response to jejunectomy, we measured polyamine concentrations and the activities of ODC, DAO and alkaline phosphatase (a marker of enterocyte maturity) in epithelial cells isolated by the Weiser technique from villus tips, mid villi, lower villi and crypts 4 days after surgery in transected control (TRC) and jejunectomised rats untreated or given the specific ODC blocker, alpha-difluoromethyl ornithine (DFMO, 2% in drinking water beginning 3 days before surgery). In the TRCs, there was a diminishing villus tip-to-crypt gradient not only in alkaline phosphatase but also in ODC and DAO activities. After jejunectomy, there were up to 93% increases in mean enterocyte ODC activity when compared with the corresponding cell fractions from the TRCs, but in both the control and jejunectomised rats, DFMO treatment markedly inhibited ODC activity (p < 0.05-0.01) and reduced spermidine and particularly putrescine concentrations (p < 0.005-0.001) in all four cell fractions. Only 4 days post-operation, jejunectomy stimulated a significant increase in ileal wet weight but DFMO treatment completely prevented this adaptive resonse and significantly reduced segmental intestinal weight (mg/cm) in the TRCs. These results (i) extend our knowledge of polyamines and related enzymes along the villusxrypt gradient in the normal intestine, (ii) provide the first data on these variables after resection, and (iii) lend further support to the hypothesis that changes in enterocyte ODC activity and in putrescine and spermidine concentrations play an important role in initiating the ileal adapative response to proximal small bowel resection in the rat. © 1990 S. Karger AG, Basel.