Effect of experimental stress on the small bowel and colon in healthy humans

Abstract

BackgroundSymptoms of irritable bowel syndrome (IBS) are frequently reported to be exacerbated by stress. Animal studies suggest that corticotrophin releasing hormone (CRH) mediates the effect of stress on the bowel. We have shown that stressed IBS patients with diarrhea have constricted small bowels. We hypothesized that we could mimic this effect by applying experimental stress in the form of either hand immersion in ice water or CRH injection in healthy volunteers (HV).MethodsThe postprandial effect of the cold pressor test (repeated hand immersion in ice cold water) and injection of CRH, were assessed vs control in two groups of 18 HVs.Key ResultsCRH produced a significant rise from baseline salivary cortisol levels (p = 0.004) not seen with the cold pressor test. Small bowel water content (SBWC) fell postprandially on all four treatments. SBWC was significantly reduced by both stressors but CRH caused a greater effect (anova, p < 0.003 vs p = 0.02). Ascending colon (AC) volume was greater after CRH injection compared with saline (p = 0.002) but no differences were seen with the cold pressor test vs warm water. Postprandial increase in colon volume was also reduced by CRH which also increased the sensations of distension and bloating.Conclusions & InferencesTwo experimental stressors were shown to constrict the small bowel, mimicking the effect previously seen in IBS-D patients. CRH increased the volume of the AC. We speculate that stress accelerates transfer of water from the small bowel to the AC.

Corticotropin-releasing factor increases ascending colon volume after a fructose test meal in healthy humans: a randomized controlled trial

“…We hypothesized that accelerated transit, by reducing the time for absorption, would exacerbate fructose malabsorption and increase colonic volumes. Our study confirmed earlier studies that used the same MRI technique, which showed that CRF reduced SBWC (15). It should be noted, however, that because we used a very different meal, the shape of FIGURE 4 Mean 6 SEM SBWC for 20 volunteers after intravenous injection of CRF (C, solid connecting line) or saline (n, dashed connecting line), followed by a fructose drink.…”

“…Previous animal studies showed an acceleration of whole gut transit with stress and suggested that corticotropin-releasing factor (CRF) is a key element, because a CRF antagonist can block this acceleration (13,14). Recently we showed that CRF injections constricted the small bowel in healthy volunteers to a degree seen in IBS-D patients, suggesting that a similar mechanism might be operating in humans (15). Our previous MRI study showed that 40 g fructose distended the small bowel, increasing its volume 4-fold.…”

“…This dose of 40 g was selected because our previous study (16) showed that with a 40-g dose, good distension of the small bowel is obtained and easily seen on the MRI. Volunteers received serial scans after this at times 15,45,75,105,135,195,255, and 315 min postprandially, with samples of saliva for cortisol measurement, end expiratory breath for hydrogen measurement (Gastro + Gastrolyzer, Bedfont Scientific), and symptom questionnaires all being collected after each scan. Pulse and blood pressure measurements were taken after each scan, and a State-Trait Anxiety Inventory (STAI) questionnaire was administered on a single occasion halfway through the scan day.…”

“…This indicates that by using 15 participants, we should have been able to detect a 27% change in SBWC with 90% power and a ,0.05. Another study that previously used CRF showed a reduction in SBWC by 36% in 15 healthy subjects when CRF was given intravenously (15). To allow for dropouts, 20 participants were enrolled in the study.…”

A novel semi-automatic segmentation method for volumetric assessment of the colon based on magnetic resonance imaging

“…However, these studies do not report on the volume of the colon. More recent studies comparable to our study use manual segmentation to obtain regional colonic volumes from MRI [9,11,12,30]. These studies found colonic volumes within the range of our results and a wide variation in colon morphology between subjects.…”