Evidence for an enterotropic hormone: compensatory hyperplasia in defunctioned bowel.

The relative contributions of luminal and systemic factors to the development of compensatory intestinal hyperplasia were assessed by comparing the adaptive response to jejunal resection in functioning and defunctioned ileum. In Thiry--Vella loops of upper ileum, mucosal contents of RNA and DNA increased by 16--21 per cent 2--7 days after jejunectomy (P = 0.05--0.01), but DNA specific activity was unchanged. In lower ileum remaining in continuity with the nutrient stream, nucleic acids were elevated by 27--86 per cent (P less than 0.001) and specific activity by 34--36 per cent (P = 0.05--0.005). Proximal to the site of resection, duodenal hyperplasia was equally rapid but less intense than in the distal bowel. Full adaptation requires both intraluminal nutrients and enterotropic hormones to be present.