Inhibitory effect of pancreastatin on pancreatic exocrine secretions. Pancreastatin inhibits central vagal nerve stimulation.

The effects of the C-terminal fragment of rat pancreastatin on exocrine pancreatic secretions induced by several neural stimulations [IV injection of 75 or 15 mg/kg of 2-deoxy-D-glucose (central vagal nerve stimulation), injection of 2 mg of cisapride (proposed to elicit acetylcholine release from cholinergic nerve ending), and infusion of 1 or 3 mg.kg-1.h-1 of bethanechol (direct stimulation of acinar cells)] were examined in conscious rats. Rats with external bile and pancreatic fistulae were used. All the stimulations caused significant increases in pancreatic exocrine secretions. Pancreastatin at 100 pmol.kg-1.h-1 inhibited pancreatic secretions stimulated by IV injection of 2-deoxy-D-glucose but not those induced by the infusion of bethanechol or the injection of cisapride. Because these findings showed that pancreastatin inhibited pancreatic secretions induced by central vagal nerve stimulation, the effect of pancreastatin on cholecystokinin-stimulated pancreatic secretions in vagotomized rats was examined. Pancreastatin at 100 pmol.kg-1.h-1 did not inhibit pancreatic secretions stimulated by cholecystokinin octapeptide at 100 pmol.kg-1.h-1 in conscious rats after bilateral truncal vagotomy. These results suggest that pancreastatin inhibits pancreatic exocrine secretions by inhibiting vagal efferent nerve activity.