[Experimental study of the whole body response in rabbits by linear oscillatory acceleration and/or optokinetic stimulation]

[Article in Japanese]

Wada Y.

Department of Otolaryngology, Nara Medical College.

Motion sickness may be defined as an abnormal body response caused to certain kinds of motion in normal subjects. Although we know etiologic factors and symptoms of motion sickness, the mechanism of motion sickness remains unknown. To clarify some characteristics of motion sickness in rabbits, we observed responses of the autonomic nervous system consisting of a change in heart rate (HR), coefficient of variation of R-R interval (CV-RR), and serum adrenaline (AD) -and free fatty acid (FFA) concentrations during linear oscillatory acceleration and/or optokinetic stimulation. The following results were obtained as 1. Although transverse and vertical linear oscillatory accelerations affected little the body responses, longitudinal linear oscillatory acceleration diminished HR and increased CV-RR and FFA. 2. Since injection of atropine or labyrinthectomy reduced the changes of HR and CV-RR induced by longitudinal linear oscillatory acceleration the responses may originate from the vestibulo-parasympathetic nerve reflex. 3. An increase of FFA during longitudinal linear oscillatory acceleration indicates that sympathetic nerve as well as parasympathetic nerve activities are elevated. 4. In this study optokinetic stimulation was not so influential as linear oscillatory acceleration for provoking motion sickness in rabbits. 5. Concomitant stimulations of optokinetic and vestibular inputs enlarged variations of these responses.

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[Antiepileptic drugs in the combined medicinal prevention of motion sickness]

[Article in Russian]

Karkishchenko NN, Dimitriadi NA.

Different antiepileptic drugs were tested as ingredients of various combinations for the prophylaxis and therapy of motion sickness. The combinations included diphenine, depakene, diazepam, clonazepam, pantogam and pyracetam. The best antimotion effect was recorded when a combination of diphenine and pantogam was used. This combination prevented disorders of cerebral associative processes induced by simulated motion sickness.

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Effects of serotonin antagonists on motion sickness and its suppression by 8-OH-DPAT in cats.

Lucot JB.

Wright State University, Department of Pharmacology, Dayton, OH 45435.

This investigation evaluated the antagonist properties of (-)propranolol, (+)propranolol, metergoline and BMY 7378 on the known effect of 8-OH-DPAT (DPAT) to decrease motion sickness in cats. (-)Propranolol produced a greater decrease in the antiemetic effect of DPAT than did (+)propranolol. Although metergoline produced a decrease in the antiemetic effect of DPAT, the decrease could not be clearly attributed to interactions with 5-HT1A receptors because metergoline alone slightly enhanced motion sickness. Depletion of 5-HT with PCPA produced a weaker, nonsignificant enhancement of motion sickness, while mesulergine had no effect. As neither nonspecific 5-HT receptor blockade with metergoline nor depletion of 5-HT mimicked the antiemetic effect of DPAT, it was concluded that DPAT acts on postsynaptic 5-HT1A receptors to prevent emesis. BMY 7378 alone decreased the incidence of motion sickness. A dose just below this agonist range did not decrease the effects of DPAT.

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Effects of anti-cholinergic and cholinergic drugs on habituation to motion in rats.

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

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

The effects of the anti-cholinergic drug scopolamine, an anti-motion sickness drug, and of the cholinergics physostigmine and neostigmine on habituation to motion sickness in rats were examined using pica, measured as eating of kaolin, as a behavioural index of motion sickness in rats. Rats were rotated around two axes for 1 h once a day for 10 or 11 days. Rotation-induced kaolin intake of control rats gradually decreased from day 9 of daily rotation. Test rats were not treated for the first 3 days, given drugs on days 4-7 of rotation and then again given no drugs for the next 3 or 4 days. Rotation-induced kaolin intake of test rats was compared to that of controls. Results showed that TTS (Transdermal Therapeutic System)-scopolamine administration facilitated habituation to rotation, whereas physostigmine, a centrally acting cholinesterase inhibitor, suppressed it, and neostigmine, a peripherally active cholinesterase inhibitor, had no effect on habituation at all. These findings suggest that the central cholinergic neuron system plays an important role in the neural mechanism of habituation to motion in rats.

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Instability of ocular torsion in zero gravity: possible implications for space motion sickness.

Diamond SG, Markham CH, Money KE.

UCLA School of Medicine, Department of Neurology 90024-1769.

Inherent asymmetries of the gravity-sensitive otolith organs of the inner ear may be well-compensated in ordinary 1 G, but rendered unstable in novel gravitational states. Several aspects of ocular counterrolling and spontaneous eye torsion, reflexes governed by the otoliths, were examined during the hypo- and hypergravity in parabolic flight on the NASA KC-135 aircraft. Among the subjects were two astronauts, one who had suffered space motion sickness during his mission and one who had not. Using an observed separation of scores of torsional instability at 0 G as the criterion, we divided our 10 subjects into the 5 highest and 5 lowest scorers, reminiscent of the approximately 50% who do and the 50% who do not experience space motion sickness (SMS). The astronaut who had had SMS was in the high group; and the one who had not was in the low group. At 1.8 G, the groups defined at 0 G were significantly different in the instability measure. They were also significantly different at both 0 G and 1.8 G in another measure, that of torsional variability. There were no differences between the groups in amplitude of eye torsion in 0 G or 1.8 G. None of the tests were significantly different in 1 G. The results suggest that these tests of eye torsion on the KC-135 might differentiate those who would experience SMS from those who would not. Proof of this speculation awaits replication of the study using only astronaut subjects.

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The susceptibility of rhesus monkeys to motion sickness.

Corcoran ML, Fox RA, Daunton NG.

Life Sciences Division, NASA Ames Research Center, Moffett Field, CA 94086.

The susceptibility of rhesus monkeys to motion sickness was investigated using test conditions that are provocative for eliciting motion sickness in squirrel monkeys. Ten male rhesus monkeys and ten male Bolivian squirrel monkeys were rotated in the vertical axis at 150 degrees/s for a maximum duration of 45 min. Each animal was tested in two conditions, continuous rotation and intermittent rotation. None of the rhesus monkeys vomited during the motion tests but all of the squirrel monkeys did. Differences were observed between the species in the amount of activity that occurred during motion tests, with the squirrel monkeys being significantly more active than the rhesus monkeys. These results, while substantiating anecdotal reports of the resistance of rhesus monkeys to motion sickness, should be interpreted with caution because of the documented differences that exist between various species with regard to stimuli that are provocative for eliciting motion sickness.

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Hormonal changes after parabolic flight: implications on the development of motion sickness.

Drummer C, Stromeyer H, Riepl RL, Konig A, Strollo F, Lang RE, Maass H, Rocker L, Gerzer R.

Medizinische Klinik Innenstadt, Universitat Munchen, FRG.

Twenty-two different humoral parameters including stress-, gastrointestinal- and volume-regulating hormones were measured before and within 45 min after parabolic flight maneuvers of twenty healthy adult subjects. We compared hormonal data of motion sickness-affected participants with those unaffected. Changes in cortisol and vasoactive intestinal peptide plasma levels were significantly different (p less than 0.002 and p less than 0.004) between the two groups with increasing plasma levels of both hormones during motion sickness but decreasing levels within the control group. Growth hormone and prolactin plasma levels increased by 400% and 115% within the motion sickness-affected group and to a smaller degree (120% and 40% increases, respectively) within the control group, while ACTH levels were almost unchanged within both groups. Pancreatic polypeptide and gastrin plasma levels as well as plasma levels of insulin and C-peptide were significantly decreased within both groups after the parabolic flight. Plasma renin, aldosterone, atrial natriuretic peptide and cyclic GMP levels were unchanged within the control group. Within the motion sickness-affected group, plasma renin and aldosterone levels were decreased and atrial natriuretic peptide levels increased after the flight. Humoral parameters of the thyroid gland were neither changed within the groups nor different between the groups. The present data confirm previous results that increases in plasma levels of certain stress hormones participate in motion sickness. Furthermore, increases in vasoactive intestinal peptide levels participate in motion sickness. These increases could explain some of the gastrointestinal symptoms in motion sickness and might serve as markers for a discrimination between regular stress and motion sickness.

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Catecholaminergic responses to rotational stress in rat brain stem: implications for amphetamine therapy of motion sickness.

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

Department of Otolaryngology, Osaka University Medical School, Japan.

The fact that amphetamine, a noradrenaline releaser, prevents motion sickness leads the hypothesis of Wood and Graybiel that the noradrenergic neuron system in the brain stem acts against the development of motion sickness. To evaluate the hypothesis, the effects of rotational stress on the turnovers of noradrenaline and dopamine in the rat brain stem were examined. Rats were rotated about two axes simultaneously (double rotational) or about one axis (single rotation) for 60 min. Measurement of kaolin intake (pica) induced by rotation, as an index of motion sickness, showed that double rotation produced motion sickness, whereas single rotation did not. Both single and double rotation significantly increased the turnovers of noradrenaline and dopamine in the brain stem. However, there were no significant differences between the increases in catecholamine turnover induced by double and single rotations. Moreover, pretreatment of rats with methamphetamine (5 mg/kg) just before double rotation, which prevented the induction of motion sickness by double rotation, did not affect increases of the catecholamine turnover in the brain stem by double rotation. These findings do not support the hypothesis of Wood and Graybiel, suggesting that the catecholaminergic neuron systems in the brain stem are not involved in motion sickness and that the therapeutic effect of methamphetamine is not due to its direct effect on the brain stem.

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