Effect of esophagus distension on gastric blood flow, gastrin and somatostatin secretion in rat

Abstract Introduction: There are many studies about the inhibitory effect of the esophageal distention (ED) on gastric motility. Recently, it has been shown that ED decreases the gastric secretions. It is well established that the inhibitory effect of ED is mediated by activation of vago-vagal inhibitory reflex. However, there is not any investigation about the effect of the reflex on the gastric blood flow and release of gastric hormones. The aim of this study was to investigate the effect of esophageal distention (ED) on gastric blood flow and release of gastrin and somatostatin hormones. Methods: In this study 79 male Wistar rats (175-230 g) were used. deprived of food but not water 24 h before the experiments. Under urethane anesthesia (1.2 g/kg, i.p.), animals underwent tracheostomy and laparotomy. A catheter was inserted in the stomach through duodenum for gastric distension. The esophagus was cannulated with a balloon orally to distend distal portion of esophagus (0.3 ml, 10 min). Saline was used for gastric distension (1.5 ml/100 g, b.w., pH 7 and 37 °C). Gastric blood flow was measured by a Laser Doppler flowmeter. Gastrin serum and somatostatin plasma levels were assessed by RIA method. Vagotomy was carried out in a group to reveal the role of vagus nerve in this action. Results: ED reduced the blood flow of gastric proximal portion (P<0.001) but the antrum blood flow was unaffected by ED. Cervical vagotomy abolished the inhibitory effect of the ED on the proximal area blood flow. Gastrin serum level and somatostatin plasma level were unaffected by ED. Conclusion: Removal of the inhibitory effect of ED after vagotomy shows that the vagus nerve was involved in the inhibitory effect on gastric blood flow. Keywords: Esophageal distension, Gastric blood flow, Vagus nerve, Rat, Gastrin, Somatostatin