Effect of fasting and feeding on polyamines and related enzymes along the villus: crypt axis

Fasting and feeding have profound effects on crypt cell production and small bowel mucosal growth but the mechanism whereby food stimulates villus tip enterocytes to influence crypt cell production is unknown. We therefore measured the activities of ornithine decarboxylase (ODC), diamine oxidase (DAO) and alkaline phosphatase (ALP--a marker of enterocyte maturity) and polyamine concentrations in epithelial cells from villus tips, mid villi, lower villi and crypts of small intestine in non-fasted controls and 18-24 h fasted rats. Fasting reduced crypt cell production and caused villus hyperplasia, DAO activity (mU/g) increased in control villus tips from 9.6 +/- (SEM) 0.8 to 12.3 +/- 1.5 after fasting (NS), from 7.6 +/- 0.4 to 13.9 +/- 3.0 in mid villi (p less than 0.01), from 5.7 +/- 1.0 to 10.4 +/- 7.4 in lower villi (p less than 0.01) and from 5.4 +/- 0.9 to 12.8 +/- 1.5 in the crypts (p less than 0.001). ALP showed a similar pattern of results. In contrast, fasting lowered ODC activity (pmol/mg protein/h) dramatically from 319 +/- 82 in control villus tips to 16.7 +/- 3.0 during fasting, from 297 +/- 59 to 10.7 +/- 3.6 in mid villi, from 224 +/- 45 to 6.3 +/- 2.8 in lower villi and from 150 +/- 31 to 5.8 +/- 3.3 in the crypts. Fasting reduced putrescine concentrations in all fractions but particularly in the crypts and in general was associated with increases in spermidine and spermine concentrations. The role of DAO in the maintenance of low putrescine concentrations during fasting is unclear.