The inner ear is a barometric pressure sensor—change in barometric pressure induces vestibular ganglion cell activation in mice

This immunohistochemical study evaluated the activity of primary sensory neurons in the vestibular ganglion in response to lowered barometric pressure (LBP) in mice to assess whether changes in barometric pressure were perceived by the vestibular system. Mice were anesthetized and exposed to three consecutive barometric pressure drops within the range of natural weather variations (-20 hPa from the atmospheric pressure). Following anesthetization and paraformaldehyde perfusion 1-hour post-LBP exposure, activity-regulated cytoskeleton-associated protein (Arc) immunoreactive cells in the superior vestibular ganglion (SVG) and inferior vestibular ganglion (IVG) were counted bilaterally and compared with those of controls. In the positive control study, anesthetized mice were placed in the prone position and subjected to rotary motion (RM). The total number of Arc-positive neurons in the IVG, but not in the SVG, was significantly higher in LBP-exposed mice than in controls, regardless of sex. The total number of Arc-positive neurons in the SVG, but not in the IVG, was significantly higher in RM-stimulated mice than in controls. These data showed that primary sensory neurons in the IVG responded to LBP, strongly suggesting that changes in barometric pressure might be perceived by the saccule or posterior semicircular canal innervated by IVG neurons in mice.