Mineralocorticoid and glucocorticoid receptors in the mammalian inner ear: a scoping review

Abstract

Mineralocorticoid (MR) and glucocorticoid (GR) receptors regulate stress and inflammation pathways relevant to hearing and balance, as well as corticosteroid treatments. However, translation to clinical outcomes remains inconsistent, likely due to biologically significant species-, strain-, and tissue-specific differences in receptor distribution. We performed a scoping review to analyze the presence, cellular and subcellular localization, and regional expression of MR and GR in the mammalian inner ear. Searches of PubMed, Web of Science, and ScienceDirect without date limits identified original studies reporting MR or GR localization or expression in cochlear or vestibular tissues. Twenty-three studies met the criteria. Both receptors were found in various cochlear and vestibular regions across species, indicating widespread corticosteroid signaling in the inner ear. Nonetheless, the data were unevenly distributed, with limited human data mainly focusing on GR, while MR was less characterized, especially in vestibular tissues and in humans. GR localization varied across strains and developmental stages, particularly in rodents, and methodological heterogeneity complicated cross-study comparisons. Overall, the literature suggests a broadly conserved yet incomplete map of corticosteroid receptor distribution in the mammalian inner ear, which affects model choice and the interpretation of translational steroid studies.

Keywords: Cochlea; Glucocorticoid receptor; Inner ear; Mineralocorticoid receptor; Strain differences; Translational otology; Vestibular system.