Altered visceral perceptual and neuroendocrine response in patients with irritable bowel syndrome during mental stress

Abstract

Background and aims: Stress often worsens the symptoms of irritable bowel syndrome (IBS). We hypothesised that this might be explained by altered neuroendocrine and visceral sensory responses to stress in IBS patients.

Subjects and methods: Eighteen IBS patients and 22 control subjects were assessed using rectal balloon distensions before, during, and after mental stress. Ten controls and nine patients were studied in supplementary sessions. Rectal sensitivity (thresholds and intensity-visual analogue scale (VAS)) and perceived stress and arousal (VAS) were determined. Plasma levels of corticotropin releasing factor (CRF), adrenocorticotropic hormone (ACTH), cortisol, noradrenaline, and adrenaline were analysed at baseline, immediately after stress, and after the last distension. Heart rate was recorded continuously.

Results: Thresholds were increased during stress in control subjects (p<0.01) but not in IBS patients. Both groups showed lower thresholds after stress (p<0.05). Repeated distensions without stress did not affect thresholds. Both groups showed increased heart rate (p<0.001) and VAS ratings for stress and arousal (p<0.05) during stress. Patients demonstrated higher ratings for stress but lower for arousal than controls. Basal CRF levels were lower in patients (p<0.05) and increased significantly during stress in patients (p<0.01) but not in controls. Patients also responded with higher levels of ACTH during stress (p<0.05) and had higher basal levels of noradrenaline than controls (p<0.01). Controls, but not patients, showed increased levels of adrenaline and noradrenaline in response to stress (p<0.05).

Conclusions: Stress induced exaggeration of the neuroendocrine response and visceral perceptual alterations during and after stress may explain some of the stress related gastrointestinal symptoms in IBS.

Figure 1

Experiment protocol (see text for details). VAS, visual analogue scale.

Figure 2

Sensory thresholds (mean (SEM)) for rectal fullness (A), defecatory urge (B), and discomfort (C) during the distension sequences before stress (1), during stress (2), and after stress (3) in series I experiments in patients and controls. Thresholds were increased in controls during stress compared with before and after. In patients, only thresholds after stress differed from the stress period. *p<0.05 **p<0.01.

Figure 3

Mean heart rate during the distension sequences (1, 2, and 3) and the resting periods in between, in patients and controls. An increase was observed in both groups during stress. ***p<0.001.

Figure 4

Visual analogue scale (VAS) ratings of perceived stress (A) and arousal (B) (median (interquartile range (IQR)) during the separate distension sequences in series I experiments in patients and controls. Both groups reported higher ratings of both stress and arousal during the stress period. Compared with controls, patients demonstrated higher ratings for stress but lower for arousal. *p<0.05, **p<0.01, ***p<0.001.

Figure 5

Levels of corticotropin releasing factor (CRF) (A), adrenocorticotropic hormone (ACTH) (B), and noradrenaline (C) (mean (SEM)) at baseline (1), after stress (2), and at the end of the experiment (3) in patients and controls. Patients had lower basal levels of CRF but showed a stress provoked increase in both CRF and ACTH that was not seen in controls. Basal levels of noradrenaline were higher in patients, but controls and not patients demonstrated increased levels in response to stress. *p<0.05.