Xylazine emesis, yohimbine and motion sickness susceptibility in the cat.

Lucot JB, Crampton GH.

The possible role of the alpha-2 adrenoceptors in xylazine-induced vomiting and in motion sickness was investigated. Cats were divided into two groups according to motion sickness susceptibility and were observed after s.c. injections of xylazine. The incidence of vomiting increased with the dose, and at each dose, the high susceptibility group had a greater emetic incidence than the low susceptibility group. In another experiment with cats divided into two groups according to motion sickness susceptibility, s.c. administration of yohimbine effectively antagonized the xylazine-induced emesis in both susceptibility groups. The cats in the latter experiment were then challenged with a motion sickness stimulus, after s.c. pretreatment with yohimbine. Yohimbine failed to prevent motion sickness but did occasion an unexplained variability in the incidence of vomiting. These findings suggest that the emetic effect of xylazine results from stimulation of alpha-2 adrenoceptors but that these receptors are not fundamental to feline motion sickness. The fact that susceptibilities to xylazine-induced emesis and to motion sickness are correlated suggests a point of interaction other than the area postrema, which is known to be essential for xylazine-induced vomiting but not for motion sickness in the cat.

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Subjective concomitants of motion sickness: quantifying rotation-induced illness in squirrel monkeys.

Wilpizeski CR, Lowry LD, Green SJ, Smith BD Jr, Melnick H.

Department of Otolaryngology, Thomas Jefferson University Medical College, Philadelphia, PA 19107.

It has been suggested by numerous researchers that the development of conditioned food aversion (CFA) in experimental animals represents the presence of a subjective state of illness. Squirrel monkeys with proven susceptibility to rotation-induced vomiting were given surgical bilateral labyrinthectomies, a procedure known to abolish signs and symptoms of motion sickness in human beings. Postoperatively, labyrinthectomized monkeys neither vomited nor revealed any reduction in food consumption when exposed to provocative rotation. Other samples of monkeys known to be refractory to horizontal rotation and to sinusoidal vertical motion also exhibited little tendency to acquire a conditioned aversion to banana. But monkeys who had sham operations and those who revealed weak-to-strong signs of motion sickness exhibited a marked CFA (significant reduction in food intake). The strength of CFA was much greater when elicited in the test vehicle when compared with response in the home cage. The findings are interpreted as support for a limited application of CFA procedures for inferring the presence of motion-induced nausea and malaise.

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Unusual visual stimulation in dynamic balance conditions: proposal for a space motion sickness test.

Severac A, Bessou P, Pages B.

Laboratoire de Physiologie, Universite Paul Sabatier, Toulouse, France.

We previously demonstrated the efficiency of normal vision/unusual vestibular cues conflict to induce motion sickness. In the present study, we investigate whether, inversely, unusual visual information/normal vestibular function conflict also elicited motion sickness. The experiments were again carried out in dynamic balance conditions to increase proprioceptive input. Circular translation of the visual field with diplopia were produced by rotating Fresnel prismatic glasses. The stimulation triggered SMS-like symptoms and dynamic balance disturbance. A positive relationship was found between discomfort and balance disturbance. Unusual visual information should therefore be included in Space Motion Sickness susceptibility testing.

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[Participation of endogenous opioid peptides in the pathogenesis of motion sickness]

[Article in Russian]

Iasnetsov VV, Vakulina OP, Sabaev VV, Mokrousova AV, Karsanova SK.

Investigations were performed with 19 healthy male volunteers to specify a possible role of endogenous opioid peptides in the pathogenesis of motion sickness. For this purpose the test subjects were administered naloxone, a specific antagonist of opiates and opioids, before rotation and during rotation in a BU-4 armchair at a rate of 30 rpm. In addition, the content of beta-endorphin in blood plasma was measured. It was discovered that naloxone exerts both prophylactic and therapeutic effects as regards the simulated motion sickness. In this respect it was more efficacious than the reference drug scopolamine. After rotation there was a significant increase in the beta-endorphin content in the blood plasma of the test subjects. It is assumed that endogenous opioid peptides (in particular beta-endorphin) may be directly involved in the genesis of vestibulo-vegetative disorders in motion sickness.

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The role of motion sickness in predicting anticipatory nausea.

Leventhal H, Easterling DV, Nerenz DR, Love RR.

Department of Psychology, University of Wisconsin, Madison 53706.

Susceptibility to motion sickness has been demonstrated to be a predictor of anticipatory nausea in cancer patients receiving chemotherapy. However, previous research did not test whether motion sickness increases anticipatory nausea only by increasing the base rate of posttreatment nausea and vomiting (which has traditionally served as the unconditioned stimulus in the conditioning model for anticipatory nausea) or, alternatively, whether motion sickness might facilitate the association of external stimuli to posttreatment nausea and vomiting. Using two different analytic approaches--a series of logistic analyses that controlled for drug-induced nausea and vomiting following the initial injection, along with an event history analysis which allows for updating on the posttreatment nausea and vomiting factors--motion sickness was found to be an independent predictor of anticipatory nausea. Further, the predictive power of motion sickness is also independent of the effects of pretreatment anxiety, taste during injection, and age.

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Motion sickness and anxiety.

Fox S, Arnon I.

Department of Psychology, Bar-Ilan University, Ramat-Gan, Israel.

Ninety-four Israeli pilot trainees completed a battery of anxiety related questionnaires: Taylor Manifest Anxiety Scale, EPQ, 16PF, and Spielberger's State and Trait Anxiety Scores. Self reports and flight instructor observations of motion sickness symptoms were collected after initial flights. No significant correlations were found between these two sources. Anxiety scores derived from the battery of anxiety questionnaires were correlated with self reports of motion sickness but not with instructor observations. Discussion focused on the potential limitations of external observers in assessing motion sickness, the convergence of anxiety assessments, and the overlap between anxiety and motion sickness symptoms. Methodological and practical implications conclude the review.

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Effects of anti-motion sickness drugs on motion sickness in rats.

Morita M, Takeda N, Kubo T, Yamatodani A, Wada H, Matsunaga T.

Department of Otolaryngology, Osaka University School of Medicine, Japan.

Pica, the eating of nonnutritive substances such as kaolin, can be induced by rotation in rats. We used this rotation-induced pica as a behavioral index of motion sickness in rats and examined whether diphenhydramine, methamphetamine and scopolamine, which are anti-motion sickness drugs for humans, are effective for reducing motion sickness in rats. Intraperitoneal injection of diphenhydramine or methamphetamine suppressed the rotation-induced kaolin intake of rats. Intraperitoneal injection of scopolamine had no effect on the rotation-induced kaolin intake, but its transdermal administration reduced this kaolin intake. These findings show that human anti-motion sickness drugs also prevent motion sickness in rats. Since the pharmacological mechanisms for preventing motion sickness in rats and humans are similar, we conclude that rats are a suitable animal model for use in studies on putative anti-motion sickness drugs.

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Neuropsychiatric observations of proprioceptive sensitivity in motion sickness susceptibility.

Leimann Patt HO, Baistrocchi RL, Moia PI.

National Institute of Aviation and Space Medicine, Buenos Aires, Argentina.

The assessment of motion sickness susceptibility is still an unsolved problem, due in part to its unclear etiology. We studied 16 referred patients suffering from "idiopathic motion sickness" and 4 pilots suffering from motion airsickness. All clinical and neurological tests proved negative, including electroencephalograms, electronystagmograms, Doppler studies, and computerized tomography of the brain. Cervical spine X-rays and personality characteristics were assessed. Simultaneously, 35 asymptomatic pilots and pilot applicants were studied as controls. Both groups were exposed to cross-coupled accelerations on a Barany chair at 15 rpm along with 0.5 Hz head flexions. The pathological group showed a straightened cervical curvature as well as a significantly higher degree of malaise (scale of Graybiel and Lackner). Their personalities were highly alexithymic or obsessive compared to the control group (Kruskal-Wallis Test). Alexithymic and obsessive personalities may express their stress reactions and psychic conflicts through somatic signs, such as cervical muscle contractures; consequently, straightening the cervical spine with the subsequent alteration of proprioceptive inputs to the vestibular nuclei may increase motion sickness susceptibility.

Online pharmacy ref source: www.ncbi.nlm.nih.gov/entrez/query.fcgi?cmd=Retrieve&db=PubMed&list_uids=3202792&dopt=Abstract motion sickness