Effect of chronic estradiol administration on vimentin and GFAP immunohistochemistry within the inner ear.
Recent data show that hormone replacement therapy, involving estrogen together with progestin, can promote hearing loss (Guimaraes, P., Frisina, S.T., Mapes, F., Tadros, S.F., Frisina, D.R. and Frisina, R.D., 2006. Progestin negatively affects hearing in aged women. Proc. Natl. Acad. Sci. USA. 103, 14246-14249.). But long-term estradiol treatment, which induces hyperprolactinemia in guinea pigs, results in hearing loss and bone dysmorphology of the otic capsule-without much hair cell loss (Horner, K.C., Cazals, Y., Guieu, R., Lenoir, M. and Sauze, N., 2007. Experimental estrogen-induced hyperprolactinemia results in bone-related hearing loss in the guinea pig. Am. J. Physiol., Endocrinol. Metab. 293, E1224-1232.). Since estrogen receptor beta can protect the mouse cochlea against acoustic trauma (Meltser, I., Tahera, Y., Simpson, E., Hultcrantz, M., Charitidi, K., Gustafsson, J.A. and Canlon, B., 2008. Estrogen receptor beta protects against acoustic trauma in mice. J. Clin. Invest. 118, 1563-1570.), we hypothesized that estradiol might activate protective glial-like elements in the inner ear. Immunohistochemistry showed down-regulation of vimentin within the lateral wall and upregulation within the spiral limbus. Glial fibrillary acid protein was increased in the inner sulcus, Hensen cells and Claudius cells. Furthermore, there was increased expression of vimentin in type II cells of the spiral ganglion and type I vestibular hair cells. The observations suggested that estradiol treatment may affect the inner ear ionic homeostasis but protection may be afforded via activated intermediate filaments.
Department Physiologie Neurovégétative, CRN2M-UMR 6231, Université Paul Cézanne, Avenue Normandie Niémen, 13397 Marseille Cedex 20, France. kathleen.horner@univ-cezanne.fr
Kathleen C
KC
Horner
Jean-Denis
JD
Troadec
Michel
M
Dallaporta
Juliette
J
Pio
D000818:Animals; D007758:Ear, Inner / Q000187:drug effects* / Q000378:metabolism*; D004848:Epithelium / Q000187:drug effects / Q000378:metabolism; D004958:Estradiol / Q000494:pharmacology*; D004967:Estrogens / Q000494:pharmacology*; D005260:Female; D005904:Glial Fibrillary Acidic Protein / Q000378:metabolism*; D006168:Guinea Pigs; D007150:Immunohistochemistry; D007382:Intermediate Filaments / Q000378:metabolism; D008297:Male; D009457:Neuroglia / Q000187:drug effects / Q000378:metabolism; D009474:Neurons / Q000187:drug effects / Q000378:metabolism; D009925:Organ of Corti / Q000187:drug effects / Q000378:metabolism; D013136:Spiral Ganglion / Q000187:drug effects / Q000378:metabolism; D014746:Vimentin / Q000378:metabolism*
D004967:Estrogens; D005904:Glial Fibrillary Acidic Protein; D014746:Vimentin; D004958:Estradiol