Correlation of gut hormones with irritable bowel syndrome

Irritable bowel syndrome (IBS) is a functional bowel disorder which is characterized by abdominal pain and disturbed bowel habits. The pathophysiological mechanism is complex and still remains incompletely clear. Alterations at both the central and the peripheral level are thought to contribute to the symptoms of IBS, including psychosocial factors, visceral hypersensitivity and abnormal gastrointestinal motility and secretion. Several gut peptides contribute to the regulation of gastrointestinal function, but little is known about gut hormone secretion in IBS.

We evaluated the concentrations of cholecystokinin (CCK), vasoactive intestinal peptide (VIP), somatostatin, substance P, neuropeptide Y (NPY) in plasma and in sigmoid tissue in 40 patients with IBS and 15 age- and gender-matched controls by using radioimmunoassay.

IBS patients had higher plasma level of CCK (p < 0.01), and the level of CCK in the sigmoid was also increased compared with controls (p < 0.05). The levels of somatostatin and substance P in fasting plasma and in the sigmoid were not different between IBS patients and control subjects (p > 0.05), but the levels of VIP in sigmoid tissue or in plasma were higher in IBS patients than in control group (p < 0.01). The NPY levels in both plasma and the sigmoid were significantly lower in IBS patients than in controls (p < 0.05). Plasma NPY level in patients with IBS with diarrhea as a predominant bowel pattern was lower than in patients with IBS with constipation as a predominant bowel pattern.

IBS patients have increased levels of CCK and VIP and decreased NPY levels in fasting plasma and sigmoid tissue. These alterations of VIP, CCK and NPY may play a role in the pathogenesis of IBS.