Effect of somatostatin analogue octreotide injected into the third cerebral ventricle on pentagastrin-induced gastric acid secretion in rats

Abstract

To investigate the effect of long-lasting somatostatin analogue octreotide (Oct) injected into the third cerebral ventricle (TCV) on gastric acid secretion in rats. TCVs were cannulated in male Wistar rats anesthetized with sodium pentobarbital. One week later acute gastric lumen perfusion was carried out and gastric acid was continuously washed with 37 degree Celsius saline by a perfusion pump. Gastric perfusion samples were collected every 10 min and titrated by 0.01 moL/L NaOH to neutral. On the basis of subcutaneous (sc) injection of pentagastrin (G-5, 160 microg/kg), Oct (0.025 microg, 0.05 microg, 0.1 microg, n=12 in each group) or vehicle (pyrogen-free physiological saline, n=10) was injected into the TCV. Before and after the TCV injection, 1 h total acid output (TAO) was determined and experimental data were expressed in change rate (%) of TAO. Oct (0.025, 0.05 and 0.1 microg) injected into the TCV resulted in change rate of 1.56% (P>0.05), 20.21% (P<0.01) and 37.82% of TAO (P<0.001), respectively. Moreover, comparison in change rate of TAO among these 3 doses showed P<0.05 between 0.025 microg and 0.05 microg, P<0.01 between 0.025 microg and 0.1 microg, and P<0.05 between 0.05 microg and 0.1 microg. However, sc injection of 0.05 microg Oct had no effect on G-5 stimulated gastric acid secretion. Octreotide injected into the third cerebral ventricle inhibits gastrin-induced gastric acid secretion in a dose-dependent manner.