The role of apelin in the modulation of gastric and pancreatic enzymes activity in adult rats.

Apelin is considered as important gut regulatory peptide ligand of APJ receptor with a potential physiological role in gastrointestinal cytoprotection, regulation of food intake and drinking behavior. Circulating apelin inhibits secretion of pancreatic juice through vagal- cholecystokinin-dependent mechanism and reduces local blood flow. Our study was aimed to determine the effect of fundectomy and intraperitoneal or intragastric administration of apelin-13 on pancreatic and gastric enzymes activities in adult rats. Fundectomy is a surgical removal of stomach fundus - maine site apelin synthesis. Three independent experiments were carried out on Wistar rats. In the first and second experiment apelin-13 was given by intragastric or intraperitoneal way twice a day for 10 days (100 nmol/kg b.w.). Control groups received the physiological saline respectively. In the third experiment the group of rats after fundectomy were used. Fundectomized rats did not receive apelin and the rats from control group were 'sham operated'. At the end of experiment rats were sacrificed and blood from rats was withdrawn for apelin and CCK (cholecystokinin) radioimmunoassay analysis and pancreas and stomach tissues were collected for enzyme activity analyses. Intragastric and intraperitoneal administrations of apelin-13 increased basal plasma CCK level and stimulated gastric and pancreatic enzymes activity in rats. In animals after fundectomy decreased activity of studied enzymes was observed, as well as basal plasma apelin and CCK levels. In conclusion, apelin can effects on CCK release and stimulates some gastric and pancreatic enzymes activity in adult rats while fudectomy suppresses those processes. Changes in the level of pancreatic lipase activity point out that apelin may occurs as a regulator of lipase secretion.