Intestinal chemo- and mechano-sensitivity: selective modification of small intestinal sensitivity by lipids

Intestinal chemo-nociception is a recently described mechanism of perception of intraluminal stimuli that might involve pathways independent from mechano-nociception.

To investigate whether intraluminal lipids not only modify mechano-sensitivity, but also influence chemo-sensitivity.

Nineteen healthy volunteers ingested an orojejunal tube assembly for mechanical and chemical stimulation of the proximal jejunum. Volume-controlled distension of a jejunal balloon and capsaicin perfusion were performed during simultaneous infusion of saline or a 10% lipid emulsion. A standard questionnaire evaluated quality and intensity of symptoms induced by intestinal stimulation.

Balloon volumes to induce perception thresholds were significantly reduced during lipid perfusion (P < 0.05), while balloon pressures remained unaltered (P > 0.05). Saline infusion (2.5 mL/min) did not alter thresholds of perception. Lipid infusion also increased intensity of perception during given distension volumes (P < 0.05). Lipid infusion did neither affect perception quality induced by capsaicin, nor perception thresholds, nor intensity of perception during capsaicin perfusion (P > 0.05). The quality of sensations induced by capsaicin perfusion was similar to sensations during distension, except of sensation of warmth, that was almost exclusively reported during capsaicin perfusion.

Intraluminal lipids selectively modify intestinal mechano-perception and do not alter chemo-perception. Intestinal chemo-nociception and mechano-nociception are two mechanisms of intestinal perception that involve distinct sensory pathways.