Gastric secretions are increased by all of the following except: (A) Somatostatin, (B) Histamine, (C) Vagal stimulation, (D) Gastrin
Answer is A. Somatostatin released by D cells(located adjacent to G cells)inhibits gastrin secretion by G cells. -Vagal stimulation inhibits release of somatostatin & thus indirectly stimulates H+ secretion by removing inhibitory effect of somatostatin on parietal cells. -Histamine increases H+ secretion by acting on H2 receptors on parietal cells. -Gastrin is a hormone secreted by G cells into blood circulation. It stimulates secretory activity of parietal cells & chief cells. Reference: Medical Physiology, Indu Khurana