A new nausea model in humans produces mild nausea without electrogastrogram and vasopressin changes

UNLABELLED: The standard human vection model utilized for nausea has been an optokinetic drum. This model may be difficult to extrapolate to the usual clinical setting. Our goals were to develop an experimental model which could induce low grade nausea in humans and to determine the relationship between mild nausea and changes in the electrogastrogram and plasma vasopressin concentrations. METHODS: Twenty-one volunteers (11 males, mean age: 37 years) participated. At baseline and throughout the study the electrogastrogram was monitored, blood was drawn for vasopressin assay and symptoms of nausea, dizziness and headache were rated on a 0-10-point scale. Subjects were semireclined in a darkened room while viewing moving bars of light rotating at a rate of 85 degrees s-1. Subjects were asked to rate their proneness to motion sickness and their current level of anxiety at baseline. RESULTS: Eight subjects developed mild to moderate (mean: 3.6) nausea during vection. Symptoms of nausea were correlated with a reported history of motion sickness (r = 0.49, P < 0.05) but not with anxiety (r = 0.14, P = 0.54). Degrees of nausea correlated with degrees of dizziness (r = 0.47, P < 0.05) but not with headache (r = 0.29, P = 0.14). Subjects who developed mild nausea were not significantly more likely to exhibit altered electrogastrogram or vasopressin than subjects who did not report nausea. Vasopressin levels during baseline and experimental conditions were highly correlated (r = 0.66, P < 0.005 and r = 0.55 P < 0.005, respectively) with reported baseline anxiety. CONCLUSIONS: (1) This new model in humans induced mild nausea that was unrelated to electrogastrogram and vasopressin abnormalities, (2) high correlation between anxiety and vasopressin suggests that vasopressin may not be directly related to nausea, and (3) these data indicate that onset of nausea mediated centrally can occur without associated electrogastrogram changes.