title: Gene expression pattern after insertion of dexamethasone-eluting electrode into the guinea pig cochlea.
abstract: A cochlear implant is an indispensable apparatus for a profound hearing loss patient. But insertion of the electrode entails a great deal of stress to the cochlea, and may cause irreversible damage to hair cells and related nerve structure. Although damage prevention effects of dexamethasone have been reported, long-term administration is difficult. In this study, we used a dexamethasone-eluting electrode in the guinea pig cochlea, and compared the gene expression after 7 days insertion with that of a normal electrode and non-surgically treated control by microarray. 40 genes were up-regulated 2-fold or more in the normal electrode group compared to the non-surgically treated group. Most of the up-regulated genes were associated with immune response and inflammation. In the dexamethasone-eluting group, compared to the normal electrode group, 7 of the 40 genes were further up-regulated, while 12 of them were down-regulated and there was a tendency to return to the non-surgical condition. 9 genes were down-regulated 2-fold or less with normal electrode insertion, and 4 of the 9 tended to return to the non-surgical condition in the dexamethasone-eluting group. These genes are certainly involved in the maintenance of the physiological functions of the cochlea. Our results indicate that the dexamethasone-eluting electrode will have an effect on the normalization of homeostasis in the cochlea.
authors.affiliation: Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan; Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Takumi
authors.affiliation: Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan; Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Shin-ya
authors.initials: SY
authors.lastname: Nishio
authors.affiliation: MED-EL Headquarters, Innsbruck, Austria.
authors.forename: Kenneth
authors.initials: K
authors.lastname: Mugridge
authors.affiliation: Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Tomohiro
authors.initials: T
authors.lastname: Oguchi
authors.affiliation: Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Shigenari
authors.initials: S
authors.lastname: Hashimoto
authors.affiliation: Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Nobuyoshi
authors.initials: N
authors.lastname: Suzuki
authors.affiliation: Department of Hearing Implant Sciences, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Satoshi
authors.initials: S
authors.lastname: Iwasaki
authors.affiliation: MED-EL Headquarters, Innsbruck, Austria.
authors.forename: Claude
authors.initials: C
authors.lastname: Jolly
authors.affiliation: Department of Otorhinolaryngology, Shinshu University School of Medicine, Matsumoto, Japan.
authors.forename: Shin-ichi
authors.initials: S
authors.lastname: Usami
mesh_terms: D000818:Animals; D003051:Cochlea / Q000187:drug effects / Q000378:metabolism* / Q000601:surgery*; D019929:Cochlear Implantation / Q000009:adverse effects* / Q000295:instrumentation*; D003907:Dexamethasone / Q000494:pharmacology*; D004566:Electrodes / Q000009:adverse effects; D006168:Guinea Pigs; D008297:Male; D059467:Transcriptome / Q000187:drug effects*
chemical_list: D003907:Dexamethasone