Neurochemical mechanisms of motion sickness.

Three kinds of neurotransmitters (histamine, acetylcholine, and catecholamine) are thought to be important in the neural processes of motion sickness because antihistaminics, scopolamine, and amphetamine are effective in preventing motion sickness. In this study, we examined the neurochemical and neuropharmacologic features of motion sickness in rats. Based on our results, we propose the following hypotheses for the neurochemical mechanisms of motion sickness: (1) the histaminergic neuron system is involved in the signs and symptoms of motion sickness, including vomiting; (2) the acetylcholinergic neuron system is involved in the processes of habituation to motion sickness, including neural store mechanisms; and (3) the catecholaminergic neuron system in the brain stem is not related to the development of motion sickness.