Modification of small bowel mechanosensitivity by intestinal fat

Background-Lipids may exacerbate symptoms induced by gut stimuli. Aim-To determine the mechanism whereby fat exerts this effect. Subjects-Twenty four healthy subjects were studied during fasting. Methods-We measured perception (0-6 scale) in response to jejunal balloon distension and transmucosal electrical nerve stimulation; phasic stimuli tone minute) were randomly applied at five minute intervals during intestinal infusion (2 ml/min) of saline and then Intralipid 2 kcal/min thigh fat; n=8 subjects), Intralipid 0.5 kcal/min (low fat; n=8), or saline (n=8). Results-Intestinal lipids increased the perception of jejunal distension regardless of concentration (by 53% with high fat, 49% with low fat, and 17% with saline; p<0.05 for both fat loads). This effect could not be attributed to changes in intestinal compliance as intraballoon pressures remained unchanged during Lipid infusion (2% change; NS). Sensitisation induced by Lipids seemed to be specifically related to intestinal mechanoreceptors because electrical stimulation, which non-specifically activates gut afferents, was perceived equally during saline and lipid administration (10%, 11%, and 15% change during high fat, low fat, and saline, respectively; NS). Conclusion-Physiological amounts or lipids heighten intestinal sensitivity by modulating intestinal mechanoreceptor response.