Proliferation and functional changes of pancreatic gastrin cells in neonatal rat

Introduction: Although gastrin cells are not found in the adult pancreas, they are found transiently in the neonatal pancreas. It has been suggested that gastrin may play a role in pancreatic development. However, cell kinetics as well as the fate and the role of gastrin cells are not clear. Methodology: Proliferation and functional changes of pancreatic gastrin cells in neonatal Wister rats were studied by immunohistochemistry and [H-3]thymidine autoradiography. Results: Numbers of pancreatic gastrin cells in neonatal rats showed a peak immediately after birth and then decreased rapidly. Gastrin cells were observed within approximately 2 weeks after birth in islets and within approximately 4 weeks after birth among exocrine cells. In contrast with the decrease of gastrin cell numbers, numbers of duodenal cholecystokinin cells increased remarkably after 7 days of age. Proliferative activity of acinar cells showed two peaks at age 2 days and 9 days. Despite a decrease in gastrin cell numbers, gastrin cells maintained a certain degree of proliferative activity. The "re-staining method" for gastrin and insulin revealed that immunoreactive cells for both gastrin and insulin were rarely found a few days after birth. Conclusion: These results suggest that pancreatic gastrin cells do not die off or change to another type of endocrine cell and that some gastrin cells change to insulin cells.