Publication
Title
Intranasal scopolamine affects the semicircular canals centrally and peripherally
Author
Abstract
Space motion sickness (SMS), a condition caused by an intra-vestibular conflict, remains an important obstacle that astronauts encounter during the first days in space. Promethazine is currently the standard treatment of SMS, but scopolamine is used by some astronauts to prevent SMS. However, the oral and transdermal routes of administration of scopolamine are known to have substantial drawbacks. Intranasal administration of scopolamine ensures a fast absorption and rapid onset of therapeutic effect, which might prove to be suitable for use during spaceflights. The aim of this study was to evaluate the effects of intranasally administered scopolamine (0.4 mg) on the semicircular canals (SCCs) and the otoliths. This double-blind, placebo controlled study was performed on 19 healthy male subjects. The function of the horizontal SCC and the vestibulo-ocular reflex (VOR), as well as the saccular function and utricular function were evaluated. Scopolamine turned out to affect mainly the SCCs centrally and peripherally but also the utricles to a lesser extent. Centrally, the most probable site of action is the medial vestibular nucleus (MVN), where the highest density of muscarinic receptors has been demonstrated and afferent fibers from the SCCs and utricles synapse. Furthermore, our results suggest the presence of muscarinic receptors in the peripheral vestibular system on which scopolamine has a suppressive effect. Given the depressant actions on the SCCs, it is suggested that the pharmacodynamic effect of scopolamine may be attributed to the obliteration of intra-vestibular conflict that arises during (S)MS.
Language
English
Source (journal)
Journal of applied physiology / American Physiological Society. - Washington, D.C.
Publication
Washington, D.C. : 2015
ISSN
8750-7587
Volume/pages
119:3(2015), p. 213-218
ISI
000358932800005
Full text (Publisher's DOI)
Full text (publisher's version - intranet only)
UAntwerpen
Faculty/Department
Research group
Publication type
Subject
Affiliation
Publications with a UAntwerp address
External links
Web of Science
Record
Identification
Creation 22.05.2015
Last edited 20.06.2017
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