Trophic effects on the pancreas of trypsin and bile salt deficiency in the small-intestinal lumen.

The effect of trypsin inhibitor-containing diets was studied in rats, mice, and hamsters for 30 weeks. In rats, pancreatic weight, DNA, RNA, and protein increased in response to a diet of raw soya flour (containing trypsin inhibitor). In mice, pancreatic weight, DNA, RNA and protein content increased with the same diet. Only rats developed micro- and macro-nodules. In rats, longer treatment with raw soya flour resulted in further growth in the pancreas, with ultimate development of adenomas and carcinomas of the acinar pancreas. The pancreatic changes were reversible up to 6 months of feeding the raw soya diet, but thereafter became irreversible. Pancreatic growth, similar to that produced by trypsin inhibitor, was also produced by cholestyramine, perhaps as a result of its bile salt-binding properties. We conclude that removal of proteases and bile salts from the upper small intestine results in pancreatic growth, which may become neoplastic.