CENTRAL 5-HYDROXYTRYPTAMINERGIC FUNCTION IN IRRITABLE-BOWEL-SYNDROME

Background: Psychological factors may contribute to the aetiology and exacerbation of symptoms in irritable bowel syndrome (IBS), suggesting that the central nervous system may be an important site of dysfuncti on in IBS. Hormonal responses after a serotonergic challenge assess th e functional integrity of central 5-hydroxytryptaminergic pathways and are diminished in depression. The aim of this study was to determine whether hormonal responses in IBS after a serotonergic challenge would be decreased, as in depression, or exaggerated, as have been reported in another functional gastrointestinal disorder, nonulcer dyspepsia. Methods: Fourteen IBS patients, 16 healthy volunteers, and 9 patients with inflammatory bowel disease were given 30 mg d-fenfluramine, a sel ective stimulus to central 5-hydroxytryptaminergic pathways. Results: Plasma prolactin and cortisol concentrations during the following 5 h increased to a similar extent in all three subject groups, despite inc reased levels of anxiety and depression (as scored on the Hospital Anx iety and Depression Scale and Beck Depression Inventory) in the IBS an d inflammatory bowel disease patients compared with the healthy contro ls. Base-line cortisol concentration correlated with the magnitude of affective disorder. Conclusion: In contrast to the alterations of cent ral 5-hydroxytryptamine receptor sensitivity seen in depression and no n-ulcer dyspepsia, central 5-hydroxytryptaminergic pathways function n ormally in IBS.