The objectives of this study were threefold. First, we investigated the effects of acute stressful stimuli on gastroduodenal feeding activity after a physiologic meal. Second, we explored the possible role of humoral mediators of these effects by measuring concurrently plasma levels of β-endorphin, catecholamines, and several gut peptides. Third, we wished to determine whether or not the gut responded selectively to different types of central stimuli. Thus, in 12 healthy volunteers we studied the effects of vertigo and cold pain on the gastrointestinal motor response to a solid meal. Pressure activity was recorded by a low-compliance perfusion system. Plasma concentrations of β-endorphin and gut peptides were measured by radioimmunoassay, whereas catecholamine levels were measured by highpressure liquid chromatography. Blood pressure, pulse rate, and skin conductance were also monitored. Labyrinthine vertigo (by otic stimulation with 10°C water; control, 37°C water) and cold pain (immersing hand in 4°C water; control, 37°C water) were simultaneously induced after the meal in each subject according to a 2 × 2 factorial experimental design. Cold pain and labyrinthine stimulation alone or in combination significantly reduced the antral phasic pressure response to solids while elevating plasma levels of β-endorphin and norepinephrine. These effects occurred within the first 20 min poststimulus and were associated with changes in blood pressure, pulse rate, and skin conductance. Further, in 2 of 6 individuals in whom vertigo was induced by labyrinthine stimulation, a phase 3-like burst of motor activity appeared in the duodenum and migrated aborally. We conclude that centrally acting external stimuli may severely disrupt antral feeding activity. Furthermore, concurrent elevations in plasma levels of β-endorphin and norepinephrine raise the possibility that these substances may be involved as mediators of the central effects on the gut.
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