Bombesin-induced pancreatic secretion and growth in rats: effect of proglumide, spantide and ranitidine

The effect of proglumide (400 mg/kg), spantide (400 g/kg) and ranitidine (20 mg/kg) on pancreatic secretory and trophic response to bombesin (10 micrograms/kg) was studied in the rat. Drugs were administered alone or combined with bombesin three times daily for 5 days. Saline-treated rats were used as controls. At the end of treatment, animals were anaesthetized and pancreatic juice was collected for 1 h after caerulein stimulation (1 microgram/kg intraperitoneally). Afterwards, rats were sacrificed and the weight and composition of pancreatic tissue were determined. As compared with control (saline) values, the volume of pancreatic juice and the output of trypsin and amylase were increased by treatment with bombesin. Neither proglumide nor spantide affected basal and caerulein-stimulated pancreatic exocrine secretion. Ranitidine, although unable to modify protein and enzyme content of pancreatic secretion, significantly reduced the volume of pancreatic juice in both basal conditions and after caerulein stimulation. Bombesin increased pancreatic weight as well as the protein and enzymatic contents of the gland. Neither the weight of the pancreas nor its composition were significantly affected by CCK-antagonist proglumide, the putative bombesin antagonist spantide or the H2-receptor antagonist ranitidine. These results show that bombesin has a trophic effect on rat pancreas and concomitantly increases its secretory capacity. Both effects are likely to be mediated through a direct action of the peptide on the pancreatic gland.