Effects of ghrelin on the gastroduodenal motility. (a) Effects of i.v. injection of ghrelin on the fed motor activity of the antrum and duodenum. I.v. injection of ghrelin induces the fasted pattern in the duodenum and increases the motor activity in the antrum. (b) I.c.v. injection NPY antiserum completely blocks the effect of i.v. injection of ghrelin. (c) The density of c-Fos-positive cells in the arcuate nucleus (ARC) and NTS is increased by i.p. injection of ghrelin compared to saline-injected control. (d) Summary diagram of the effects of ghrelin on the gastroduodenal motility and brain mechanism mediating its action.