In the rectum of patients with sporadic (non-specific) IBS, the densities of PYY and enteroglucagon cells have been shown to be significantly lower and those of somatostatin-secreting cells to be significantly higher in both IBS-D and IBS-C patients compared to the controls, whereas the density of serotonin-secreting cells in these patients did not differ from that in the healthy controls (19,20). Here, PYY is linked to irritable bowel syndrome.