Esophageal hypersensitivity is considered an important pathophysiological mechanism in
patients suffering form non-erosive gastro-esophageal reflux disease. Serotonin (5-HT) is
predominantly found in the central nervous system and in the gastro-intestinal (GI) tract.
5-HT plays a major role in the regulation of GI secretion, motility and sensitivity, and has
been associated with emotion regulation. Acute tryptophan depletion (ATD) temporarily reduces
the availability of tryptophan (TRP), thereby decreasing central and peripheral 5-HT
synthesis. From previous studies, ATD is known to affect GI physiology and enhance visceral
pain perception in the colon. The aim of the study was to investigate the effect of ATD on
esophageal sensitivity in healthy volunteers (HV).
Esophageal multimodal sensitivity was assessed after intragastric infusion of an amino-acid
mixture (AA-mix) containing 15 AAs with TRP (control condition) or without TRP (ATD
condition). After an incubation period of 5 hours, a probe with a polyurethane bag was
positioned in the distal esophagus. Thermal (recirculating a heated saline solution through
the bag), mechanical (increasing bag volume), electrical (2 stimulation electrodes) and
chemical sensitivity (modified Bernstein) were tested and at 3 time points blood samples were
collected for biochemical analysis. General mood was assessed by the Positive and Negative
Affect Schedule (PANAS) and the State-Trait Anxiety Inventory (STAI) questionnaires.