Diarrhea- and constipation-predominant IBS patients differ in postprandial autonomic and cortisol responses.
OBJECTIVE
As the primary link between brain and gut, autonomic and endocrine dysfunction may play a role in the pathophysiology of the irritable bowel syndrome (IBS). The aim of this study was to assess autonomic, endocrine, and symptomatic responses to food intake in diarrhea-predominant and constipation-predominant IBS patients, compared to normals.


METHODS
Twelve women with diarrhea-predominant or alternating IBS (IBS-D), 12 women with constipation predominant IBS (IBS-C), and 20 healthy women participated. GI symptoms, saliva cortisol concentration, heart rate, and heart rate variability were assessed at baseline and after a meal. Spectral analysis of heart rate variability was used as a measure of the sympathovagal regulation of the heart rate.


RESULTS
Both groups of IBS patients showed a significant postprandial increase in GI symptoms. IBS-D showed a significant increase in the low frequency/high frequency band ratio and a decrease in the high frequency band power during the first postmeal period, which was significantly different, not only from controls, but also from IBS-C. IBS-D also showed a significant postprandial increase in cortisol, which was not evident in controls or IBS-C. There was a significant correlation between the vagal response and the postprandial increase in GI symptoms in IBS-D (r = 0.6, p < 0.05).


CONCLUSIONS
These findings support the notion that the IBS symptom groups are characterized by different physiological responses to visceral stimuli, and point to a role of autonomic pathways in IBS symptomatology.
Elsenbruch
S
S
Institute for Medical Psychology, University Clinic of Essen, Germany.
Orr
W C
WC
D000328:Adult; D001341:Autonomic Nervous System / Q000502:physiology*; D017776:Autonomic Pathways / Q000502:physiology; D016022:Case-Control Studies; D003109:Colonic Diseases, Functional / Q000503:physiopathology*; D003248:Constipation / Q000503:physiopathology*; D003967:Diarrhea / Q000503:physiopathology*; D004562:Electrocardiography; D005260:Female; D006339:Heart Rate / Q000502:physiology; D006801:Humans; D006854:Hydrocortisone / Q000378:metabolism*; D019518:Postprandial Period / Q000502:physiology*; D012463:Saliva / Q000737:chemistry
D006854:Hydrocortisone