Evidence for a humoral mechanism after small intestinal resection. Exclusion of gastrin but not enteroglucagon.

It is generally agreed that the adaptive response in the residual bowel after major intestinal resection is dependent on luminal nutrition and pancreaticobiliary secretions. Recent evidence, however, suggests that humoral mechanisms, e.g., gastrin or enteroglucagon, may also play a part in this process. A 75% proximal small bowel exclusion was performed in 16 male Wistar rats and the excluded bowel was fashioned into a Thiry-Vella fistula. Half of the animals were allowed food ad libitum, while the rest were fed intravenously. The animals were killed at 12 days, and plasma, gastrin, and enteroglucagon were measured, while cell proliferation was determined by measuring the crypt cell production rate employing a stathmokinetic method using vincristine and crypt microdissection. In addition to these animals, 16 rats had a jejunal transection only, with half of these animals nourished intravenously, while the remainder were allowed food ad libitum. In the Thiry-Vella rats, plasma enteroglucagon was greater with oral feeding (566 +/- 59 pmol/L) than with intravenous feeding (120 +/- 452 pmol/L) (p less than 0.01), but gastrin levels did not differ in the two groups. In the ileum in continuity, crypt cell production rate per hour was greater in the orally fed animals (52 +/- 8) compared with the intravenously fed group (18 +/- 5) (p less than 0.001). In the excluded fistula, crypt cell production rate per hour was reduced by 23.8 +/- 2 in orally fed rats, but this was greater than in the intravenously fed group (16 +/- 1.5) (p less than 0.01). Both orally and intravenously fed transected rats had significantly lower plasma hormone levels, and reduced crypt cell production rate compared with the respective Thiry-Vella groups. This study suggests a distinct role for a humoral agent responsible for the proliferative changes seen after small bowel resection, and in this respect enteroglucagon appears more relevant than gastrin.