Signal transduction in vestibular adaptation to microgravity – A still unsolved problem

Abstract

In men and monkeys as well as adult and developing fish (Fundulus heteroclictus, Opsanus tau, Xiphophorus helleri), amphibian (Rana catesbeiana, Xenopus laevis) and rodents, microgravity cause significant behavioral, physiological and psychophysical sensitivity changes within the vestibular system. Some of these observations point to sensitization of the vestibular system during exposure to weightlessness. The review presents mechanisms that might contribute to vestibular sensitization during microgravity adaptation. They include (1) stimulus transduction within vestibular hair cells, (2) activation of immediate early genes within central afferent and efferent vestibular nuclei, and (3) modifications of cellular transcription factors' activity during early development.