Trophic effects of gastrin on the exocrine pancreas in rats

In three groups of hypergastrinemic rats with gastrojejunostomy and gastric antrum transplanted to the colon (AT), pancreatic structure and function were studied 2, 6, or 16 weeks postoperatively. Fasting serum gastrin was 658 ± 88 pg/ml in AT animals compared with 87 ± 12 pg/ml in sham-operated controls. Another group of rats prepared with antrectomy and gastrojejunostomy (A) had low serum gastrin concentrations; they were studied 12 weeks postoperatively. Pancreatic juice was collected after iv secretin or CCK and was analyzed for [HCO₃^-], [Cl^-], and protein. Pancreas histology and DNA/RNA per milligram of pancreatic protein was the same in all groups. A twofold increase in [HCO₃^-] and volume of secretion at 2 weeks in AT animals suggested that gastrin exerted a trophic effect on the ducts. By 6 weeks pancreas weight had increased, probably reflecting acinar growth. By 16 weeks pancreatic secretion was qualitatively similar to the control group, but the pancreas weights were 35% greater and absolute secretory capacities were 50% greater. In the A animals, pancreas weights and protein secretion were unchanged, but HCO₃^- secretion was impaired. We conclude that chronic endogenous hypergastrinemia produced functionally significant hyperplasia of both the duct and acinar cells.