Hypertrophy and hyperplasia in the endocrine and exocrine pancreas of rats fed soybean trypsin inhibitor or repeatedly injected with pancreozymin.

Rats were 1) fed raw soybeans for 30 days, 2) given trypsin inhibitor as drinking water for 7 days, or 3) repeatedly injected with cholecystokinin-pancreozymin (CCK-PZ) for 7 days. After all these treatments the pancreas of the animals was markedly enlarged. Microscopic examination revealed, besides hypertrophy of acinar cells, increased mitotic figures in the acinar, centro-acinar, intercalated portion and excretory duct cells. The islets of Langerhans were found conspicuously enlarged due to mitotic proliferation of B cells. The endogenous CCK-PZ released by the intraluminal trypsin inhibitor and the exogenous CCK-PZ given by injections thus exerts not only secretagogous, but also trophic effects upon the endocrine and exocrine pancreas. The exocrine pancreas likely is affected also by the increased release of insulin from the B cells stimulated by CCK-PZ.