Intestinal Dipeptidases. Development of Dipeptidase Activity in the Small Intestine of the Rat as Related to the Development of the Intestinal Mucosa

Abstract

AbstractThe development of five intestinal dipeptidase activities (L‐alanyl‐L‐glutamic acid, L‐alanyl‐L‐proline, glycylglycine, glycyl‐L‐leucine and glycyl‐L‐valine dipeptidase activity) in the rat from 15 days post coitum up to 3 weeks post partum was investigated and related to the structural development of the rat small intestinal mucosa. Very low enzyme activities were found in the period of mucosal cell proliferation (15 to 18 days post coitum). At 18 1/2 days post coitum the period of mucosal cell differentiation was commencing, and simultaneously the dipeptidase activities began increasing to reach maximal values at parturition, by which time the differentiation was finishing. Within a few hours of birth, when the newborns had suckled, an abrupt and significant fall to the relatively low adult level was observed for four of the dipeptidase activities. The fifth enzyme activity (L‐alanyl‐L‐proline dipeptidase) declined more slowly postnatally and first reached the relatively low adult level during the 3rd week post partum. The relation of the changes in the intestinal dipeptidase activities to the structural characteristics of the mucosa during the development has been discussed.