Objective: This study examined the effects of endogenous cholecystokinin (CCK) released by bombesin and FOY-305 (a synthetic inhibitor of trypsin on pancreatic regeneration in rats). Summary Background Data: Trophic gut hormones (CCK and bombesin) stimulate the growth of the normal rat pancreas. However, the influence of endogenous gut hormones on pancreatic regeneration is unclear. Methods: Male Fisher rats (n = 6 to 8 per group) were fed a protein-free diet and given ethionine (700 mg/kg intraperitoneally daily) for 8 to 9 days to induce degeneration of the pancreas. Regeneration was stimulated by giving the rats a regular chow diet. The effects of bombesin (10 μg/kg three times a day for 7 days) or FOY-305 (200 mg/kg daily for 8 days) on the process of regeneration were examined. Results: At the end of the degeneration phase, there was near-total destruction of pancreatic acinar cells. Both bombesin and FOY-305 stimulated pancreatic regeneration. Growth measurements (weight and total content of DNA and protein) were significantly increased (p < 0.05) in the bombesin-and FOY-305-treated rats compared with controls. Histologic examination revealed widespread repopulation of the pancreas with acinar cells in the bombesin- and FOY-305-treated groups. The stimulating effects of both bombesin and FOY-305 on pancreatic regeneration were blocked completely by the CCK-receptor antagonist L-364,718. Growth measurements were not significantly increased in the groups of control rats or rats given L-364,718 alone. Conclusions: These results show that bombesin and FOY-305 significantly stimulated pancreatic regeneration. Because the stimulating effects of bombesin and FOY-305 on regeneration were blocked by the specific CCK-receptor antagonist L-364,718, it was concluded that this effect was mediated by endogenous CCK.
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