Expression of transient receptor potential channel melastin (TRPM) 1-8 and TRPA1 (ankyrin) in mouse inner ear

Conclusions: It has been shown that TRPMs may play a functional role in sensory cell physiology, fluid homeostasis, sensory cell death, and thermosensation in the inner ear, while TRPA1 plays an important role in sensory transduction. Objective: To study expression of TRPM1-8 and TRPA1 in the mouse inner ear. Materials and methods: The localization of TRPM1-8 and TRPA1 in the inner ear of normal and gentamicin-treated CBA/J mice was investigated by immunohistochemistry. Results: The stria vascularis displayed a positive immunofluorescent reaction to TRPM1, 2, 3, 6, and 7. In the organ of Corti, outer and inner hair cells (OHCs and IHCs) showed positive immunofluorescence to TRPM1, 2, 3, 6, 7, and 8. Spiral ganglion cells were immunoreactive to TRPM1, 2, 3, 6, 7, and 8. The nerve fibers in the spiral ganglion cells and the nerves innervating the OHCs or IHCs were noticeably immunofluorescent to TRPM8 and TRPA1. In the vestibular end organs, vestibular sensory cells showed immunofluorescence to TRPM1, 2, 3, 6, and 7. The vestibular dark cells showed immunofluorescence to TRPM1, 3, 6, and 7; only the apical portion reacted to TRPM4. The nerve fibers innervating the vestibular sensory cells were distinctly reactive to TRPM8 and TRPA1, while the vestibular ganglion cells reacted to TRPM1, 2, 3, 6, 7, and 8.