Gastrointestinal motor and myoelectric correlates of motion sickness.

Lang IM, Sarna SK, Shaker R.

Department of Medicine and Dysphagia Institute, Medical College of Wisconsin, and Surgical Research Service, Zablocki Veterans Affairs Medical Center, Milwaukee, Wisconsin 53226, USA. imlang mcw.edu

The objectives of this study were to characterize the digestive tract motor and myoelectric responses associated with motion sickness. Twenty-two cats (1.5-3.0 kg) were chronically implanted with force transducers and electrodes on the stomach and small intestine. Motion sickness was activated by vertical oscillation (VO) at +/-0.5 g and identified as salivation, licking, or vomiting. Vomiting was initiated chemically by UK-14304 (2.5-15 microg/kg iv) or CuSO4 (10-50 mg ig). We found that VO caused vomiting (45% of trials), a decrease in gastrointestinal (GI) motility (69% of trials), salivation or licking (59% of trials), bradygastria (39% of trials), retrograde giant contraction (RGC, 43% of trials), giant migrating contraction (GMC, 5% of trials), and defecation (18% of trials). The decrease in GI motility occurred with (62% of trials) or without (69% of trials) vomiting. Motion sickness was accompanied by bradygastria (52% of trials) and decreased GI motility (70% of trials). Similar events occurred after CuSO4 and UK-14304, but the incidences of responses after CuSO4 were less frequent, except for vomiting, RGC, and GMC. UK-14304 never caused GMCs or defecation. The magnitude and velocity of the RGC were the same during all emetic stimuli, and RGCs never occurred without subsequent vomiting. Supradiaphragmatic vagotomy (n = 1) or atropine (n = 2, 10 or 50 microg/kg iv) blocked the RGC, but not vomiting, due to VO. We concluded that 1) oculovestibular stimulation causes digestive tract responses similar to other types of emetic stimuli, 2) decreased GI motility and bradygastria may be physiological correlates of the motion sickness, and 3) motion sickness may not be dependent on any specific GI motor or myoelectric response.

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Variables of movement amplitude and frequency in the development of motion sickness in Suncus murinus.

Javid FA, Naylor RJ.

The School of Pharmacy, University of Bradford, UK.

The aim of the present study was to investigate the effect of different frequency and amplitude of horizontal movements to induce motion sickness and to identify gender differences and adaptation to motion stimulus in adult Suncus murinus. Each animal was subjected to a horizontal motion stimulus of 3, 7, 13, or 40 mm amplitude at a frequency of 0.5, 1, 2, or 3 Hz. The number of vomiting episodes and the latency of onset were recorded over a 10-min period. For the study of adaptation, different groups of males were exposed to repeated motion sickness (using 0.5 or 1 Hz frequency and the amplitude of 40 mm) either every 2 days for a period of 30 days, or once every week for a period of 28 days. In all animals the number of emetic episodes obtained at 1 and 2 Hz were significantly higher by 40-80% than those at 0.5 and 3 Hz using either 13 or 40 mm amplitude of movements; this was followed by shorter latency of emesis. Age-matched females were shown to be more responsive to the emetic stimuli than males as the number of emetic episodes at 1, 2, and 3 Hz (amplitude of 40 mm) were significantly higher by 33%, 42%, and 75%, respectively, than in males; this also was followed by a shorter latency of emetic response. In the study of adaptation, when used once every 2 days, by the second challenge (at 0.5 Hz) the number of emetic episodes was reduced by 62%, and to subsequent challenges emesis was absent or greatly reduced. Also, a reduction in responsiveness was observed at 1 Hz, which attained a maximum effect by the third challenge. The present results indicated that Suncus murinus is sensitive to horizontal motion stimulus, the emetic episodes were significantly greater at 1 and 2 Hz than at either a lower or higher frequency, a repeated challenge once every 2 days but not weekly reduced the number of emetic episodes, and in all experiments, age-matched female animals were more responsive than males to motion stimulus and in some experiments this achieved significance.

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The effects of age and sex on susceptibility to motion sickness.

Dobie T, McBride D, Dobie T Jr, May J.

National Biodynamics Laboratory, College of Engineering, University of New Orleans, LA 70189-0407, USA. tdobie uno.edu

BACKGROUND: The present investigation is concerned with the role of sex, age and experience in determining motion sickness susceptibility. HYPOTHESIS: Motion sickness susceptibility varies with sex and age, and may be related to the level of physical activity sustained by the individual. METHODS: Three surveys were conducted. The first included school age children (9-18 yr) and addressed motion experience and motion sickness on 13 forms of transport. The second questionnaire sought to determine whether these sex differences could be understood in terms of differential involvement in various forms of physical activity. The third survey addressed the role of age and sex effects in a college age population. RESULTS: The first study revealed significantly greater motion sickness for female as compared with male subjects on devices with which both groups were equivalent in terms of exposure history. The second study showed little relation between an individual's level of physical activity and susceptibility to motion sickness. The results of the third study were in essential agreement with the first survey and revealed no significant interactions between age and sex, suggesting that sex differences remain stable across this age range. CONCLUSION: Our conclusions regarding these surveys are that sex differences in motion sickness do not vary significantly with age and cannot be accounted for by differences in exposure to motion or physical activity. There was also little evidence for the notion that men are more reticent to report motion sickness.

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Effects of gender of subjects and experimenter on susceptibility to motion sickness.

Jokerst MD, Gatto M, Fazio R, Gianaros PJ, Stern RM, Koch KL.

Department of Psychology, The Pennsylvania State University, University Park 16802, USA.

BACKGROUND: It has been reported that females are more susceptible to motion sickness than males, but these reports have failed to take into account the possible effects of the gender of the experimenter and the subjective nature of reports of symptoms of motion sickness. To deal with the first possible confound, we used male and female experimenters. To deal with the second issue, we recorded gastric myoelectric activity so as to be able to quantify gastric tachyarrhythmia, an objective measure that has been shown previously to correlate highly with severity of symptoms. METHOD: There were 34 male and 34 female participants were assigned to either a male or female experimenter. Symptoms of motion sickness were induced by placing participants in an optokinetic drum for an 8-min baseline period followed by a 16-min rotation period. Electrogastrograms (EGGs) were continuously recorded, and reports of symptoms were obtained from the participants every 3 min during rotation. RESULTS: Comparison of male and female subjects' symptom scores revealed that females had higher symptom scores than males; however, no significant main effects for gender of the subject or experimenter were found. However, on a post-session questionnaire, females reported experiencing significantly more GI symptoms than males. Gender comparisons of the change in gastric tachyarrhythmia power from baseline to rotation yielded no significant differences. CONCLUSIONS: Females report more overall symptoms of motion sickness and significantly more GI symptoms than males, but do not show greater increases in gastric tachyarrhythmia during exposure to a rotating drum.

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[The spontaneous and evoked neuronal activity of the parietal associative cortex in cats during motion sickness]

[Article in Russian]

Pravdivtsev VA, Kozlov SB, Iasnetsov VV.

In the experiments with the cats a spontaneous and induced activity of the neurons (57) of parietal associated cortex during motion sickness was studied. It was found that after a 15 min motion sickness 54 percent of the examined neurons displayed suppression, 20 percent of neurons did an increase of spontaneous activity. Twenty-six percent of neurons did not respond to motion sickness. The dynamics of induced neuronal responses under motion sickness effect was complex, a direction of the changes in induced responses frequently did not agree with that of alterations in a spontaneous cellular activity. The more stable changes of induced responses have been in the neurons with phase responses to the fight and electrocutaneous stimulation. After 45-min effect of motion sickness, the light-stimulated responses were characterized by an increase of early and suppression of late components of a response, and the responses to electrocutaneous stimulation displayed mainly a suppression of the early components of the responses.

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beta-Endorphin and arginine vasopressin following stressful sensory stimuli in man.

Kohl RL.

Space Biomedical Research Institute NASA/Johnson Space Center, Houston, TX.

This experimentation partially defines, for the first time, the response of beta-endorphin (ENDO) in man during tests designed to elicit nausea and motion sickness. These responses are similar to those associated with arginine vasopressin (AVP) and adrenocorticotropin (ACTH) to the extent that all hormones rise in response to motion sickness (p < 0.003). Repeated exposure diminished motion-induced release of ENDO (p < 0.005) and AVP (p < 0.004) despite a three-fold increase in resistance to motion stimuli. Higher post-stress levels of AVP (p < 0.04) and ACTH (p < 0.02) were correlated with greater resistance to motion sickness. These data support the hypothesis that release of AVP is a significant link between stressful motion and motion-induced nausea and other autonomic system changes. Further, resistant individuals apparently can tolerate higher peripheral levels of AVP before nausea results. Peripheral release of ENDO and ACTH may follow release of AVP; however, given the extensive and complex functional interactions that exist between AVP and the opiate systems, it is not yet possible to define a clear role for ENDO in the etiology of motion sickness.

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The influence of age on susceptibility to motion sickness in monkeys.

Cheung BS, Money KE.

Defence and Civil Institute of Environmental Medicine, Toronto, Ontario, Canada.

A longitudinal study on the effects of age on the susceptibility to motion sickness in the squirrel monkey was carried out over a 10-year period (1982 to 1991). The typical life span of squirrel monkeys is 15 years. Ten mature male squirrel monkeys of the Bolivian subspecies were found to be susceptible to motion sickness induced by a combination of vertical oscillation at 0.5 Hz and rotation in the horizontal plane at 25 rotations per minute (RPM) in a visually unrestricted environment. Signs of motion sickness were quantified according to a rating scale based on Graybiel's diagnostic criteria. Latency to vomiting/retching and severity of sickness obtained from year 1 (baseline), 3, 5, 7 and 10 were subjected to repeated-measures design analysis. There were no significant differences in the susceptibility level (as measured by latency to vomiting/retching and cumulative sickness scores) in the monkeys throughout the 10-year period. The habituation to 7 consecutive daily exposures remained the same throughout the same period. We conclude that, in the squirrel monkeys from maturity to near the end of their life span, there is no change in susceptibility to motion sickness with aging.

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Predictive efficacy of motion sickness history for airsickness.

Lee HL, Chiou WY.

School of Nursing, National Defense Medical Center, National Defense University, Taipei, Taiwan, ROC.

BACKGROUND: Airsickness is a common problem in the early stage of flying training. It can be sufficiently severe to impair the student's flight performance and his ability to learn. Without adequate evaluation and rehabilitation, intractable airsickness symptoms will force student pilots to be permanently grounded. The purpose of this study was to evaluate the predictive efficacy of motion sickness history for airsickness of flight students. METHODS: A motion sickness history questionnaire with four different scores was used to predict airsickness of student pilots in the Air Force Academy. The questionnaire asked subjects questions about the severity and frequency of motion sickness symptom experienced in nine different motion sickness situations before and after 12 years of age. The results were grouped to four different scores. Pearson correlation and Student's t-test methods were used to evaluate the correlations of the four different scores. RESULTS: A total of 76 flight students in the class of 1997 who had under gone their flight-training course were included in this study. They were all healthy males with a mean age of 22.2 years (range, 20-24 years). The airsickness incidence of student pilots was 50%. The four different scores of motion sickness history questionnaire were highly correlated (r = 0.69-0.86, p < 0.01). The "after 12 years-of-age actually sick" score key had greater predictive validity for airsickness than the other motion sickness history questionnaire score keys and so did the "before 12 years-of-age feels sick" and "after 12 years-of-age feels sick" for no airsickness. CONCLUSIONS: The motion sickness history questionnaire was an efficient method to predict airsickness among Air Force student pilots.

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