SOMATIC STIMULATION REDUCES PERCEPTION OF GUT DISTENSION IN HUMANS

Background/Aims: Perception of gut symptoms may depend on visceral sensory modulation, but the mechanisms are poorly understood. Based on somatosensory data, we hypothesized that somatic stimulation modulates perception of gut stimuli. Methods: Perception and gut reflexes were measured in 8 healthy subjects in response to increasing gastric and duodenal distentions (stimulus-response trials) performed alone or with simultaneous application on the hand of either low (just perceivable) or high (nonpainful) transcutaneous electrical nerve stimulation (100 Hz, 100 mu s) Fixed pressure distentions were performed in stepwise increments by gastric and duodenal barostats to determine the respective thresholds for discomfort. Perception was measured by a questionnaire, and gut reflex responses were measured as isobaric volume changes by the barostats. Individual stimuli of 2 minutes' duration were randomly applied at 10-minute intervals. Results: Somatic stimuli increased the tolerance to gut distention, and this effect was more pronounced with high stimuli. The gastric threshold for discomfort was 7.3 +/- 0.5 mm Hg with high stimuli vs. 5.5 +/- 0.2 mm Hg without stimuli, and the duodenal discomfort threshold was 15.5 +/- 1.5 mm Hg with high stimuli vs. 13.5 +/- 1.4 mm Hg without stimuli; P < 0.05 for both. Somatic stimuli modified neither basal gut tone nor the relaxatory duodenogastric reflex induced by duodenal distention (gastric expansion by 203 +/- 48 mL with high stimuli and 208 +/- 73 mL without stimuli). Conclusions: Somatic stimulation reduces perception of gut distention without interfering with local and reflex gut responses.