Differential localizations of the myo-inositol transporters HMIT and SMIT1 in the cochlear stria vascularis

• Published in: Neuroscience letters Vol. 674; pp. 88 - 93
• Main Authors: Edamatsu, Midori, Kondo, Yasuhiro, Ando, Motonori
• Format: Journal Article
• Language: English
• Published: Ireland Elsevier B.V 01.05.2018
• Subjects: Endolymph; Inner ear; Osmoregulation; Rat (Brown Norway); pH; Osmoregulation; Endolymph; Rat (Brown Norway); Inner ear
• ISSN: 0304-3940; 1872-7972
• DOI: 10.1016/j.neulet.2018.03.028

•Immunoreactivity of HMIT is shown in the marginal cells and basal cells of stria vascularis.•Immunoreactivity of SMIT1 is shown in the strial basal cells facing the perilymph.•Both HMIT and SMIT1 in the stria vascularis may be involved in the homeostasis of cochlear fluids. The cochlear stria vascularis produces endolymph and thereby plays an active role in inner ear homeostasis. We recently reported that the H+/myo-inositol cotransporter (HMIT) gene is expressed in the stria vascularis. Here, we examined the protein localization of HMIT and Na+/myo-inositol cotransporter 1 (SMIT1) in the stria vascularis by immunohistochemistry. HMIT and SMIT1 were detected in the lateral wall of the cochlear duct. HMIT was widely detected throughout the stria vascularis, while SMIT1 was enriched in the strial basal cells. To examine the localization of HMIT in the stria vascularis in more detail, dissociated strial cells were immunostained, which resulted in the detection of HMIT immunoreactivity in marginal cells. These results indicate that HMIT is expressed in marginal cells and basal cells of the stria vascularis, while SMIT1 expression is enriched in basal cells. We speculate that HMIT and SMIT1 may play important roles in the homeostasis of cochlear fluids, for example by participating in pH regulation and osmoregulation.