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

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.