Development of enteropeptidase activity in mouse small intestine: influence of hormones.

The postnatal development of enteropeptidase activity has been examined on mucosal scrapping of the proximal part of the mouse small intestine. The activity was present at birth and remained low during the first 15 days of life. Then it rapidly increased reaching adult level within 2 days. Daily administration of cortisone acetate (25 micrograms X g body weight (bw)-1 X day-1), insulin (12.5 mU X g bw-1 X day-1), or epidermal growth factor (4 micrograms X g bw-1 X day-1) during 3 days to 8-day-old mice induced a premature increase of enteropeptidase. The maximal increase was observed with cortisone treatment, the enzymic activity representing 70% of the adult level. Thyroxine alone (1 microgram X g bw-1 X day-1) had no significant effect on enteropeptidase activity. Hormonal interactions have been evaluated by studying the effects of different hormonal combinations. Finally, cortisone acetate which has a major effect on this activity during suckling period was unable to influence adult small intestinal enteropeptidase activity.