Pancreatic Growth after Pancreatico-Biliary Diversion Does Not Increase the Capacity to Secrete Amylase

Abstract

Background/Aim: Cholecystokinin (CCK) stimulates secretion and evokes a hyperplastic response in the rat pancreas. The aims of this study were to measure the effect of chronic hyperCCKemia induced by pancreatico-biliary diversion (PBD) on pancreatic enzyme concentrations, on amylase secretion by dispersed acinar cells, and on the CCK-stimulated secretion of pancreatic juice in PBD-operated rats. Material and Methods: Forty-five Sprague-Dawley male rats had either PBD or sham operation 4 weeks before sacrifice or additional experiments. In the first study, 25 rats (13 PBD and 12 sham-operated rats) were either freely fed or fasted overnight before sacrifice. The pancreas was dissected out, weighed and analyzed. In the second study, the rats (6 PBD and 7 sham-operated rats) were fasted overnight before pancreatic acini were prepared. Secretion of amylase during stimulation of acini with CCK-8S and carbachol was measured. In the third study (5 sham-operated and 4 PBD rats), the rats were fasted overnight before basal and CCK-stimulated secretion was measured in vivo. Results: PBD-operated rats showed a threefold increase in pancreatic wet weight with increased contents of DNA, protein and water. The concentration of pancreatic amylase was 7–12% of that found in control animals. The concentrations of trypsin and lipase were also lowered. Stimulation of dispersed pancreatic acini with CCK-8S or carbachol resulted in secretion of amylase to a similar extent in PBD and sham-operated rats. There was no difference in the secretion of pancreatic juice in response to CCK, but although the output of amylase from PBD-operated rats increased with CCK, it remained at a low level throughout the study period. Conclusion: PBD evoked hyperplastic changes in the rat pancreas and decreased the concentrations of amylase, trypsin and lipase. However, the capacity of acinar cells to secrete amylase remained intact. The stimulated pancreatic secretion was not changed in volume, but the output of amylase was low in PBD-operated rats. The findings are consistent with the idea that the enlargement of the pancreas following PBD does not improve the secretory capacity.