Cochlear damage due to germanium-induced mitochondrial dysfunction in guinea pigs.
This investigation addressed the effect of germanium dioxide (GeO(2))-induced mitochondrial dysfunction on hearing acuity. Guinea pigs were fed chow that contained 0%, 0.15%, or 0.5% GeO(2). The animals that were fed 0.5% GeO(2) for 2 months developed hearing impairment chiefly due to degeneration of stria vascularis and cochlear supporting cells, which exhibited electron-dense mitochondrial inclusions. Cytochrome c oxidase activity was decreased in the skeletal muscles and kidney, which also exhibited electron-dense mitochondrial inclusions. No apparent pathological changes were observed in the utricle, semicircular canal, or among the vestibular nerve fibers, or in the liver or heart. The untreated animals and those treated with 0.15% GeO(2) did not exhibit hearing impairment or pathological changes in any organs. These findings suggest that administration of 0.5% GeO(2) induces mitochondrial dysfunction in the stria vascularis and supporting cells in the cochlea, as in the skeletal muscles and kidney, thereby causing hearing impairment in the guinea pigs.
Yamasoba
Tatsuya
T
Department of Otolaryngology, Head and Neck Surgery, University of Tokyo, Hongo 7-3-1, Bunkyo-ku, Tokyo 113-8655, Japan. tyamasoba-tky@umin.ac.jp
Goto
Yu-Ichi
Y
Komaki
Hirofumi
H
Mimaki
Masakazu
M
Sudo
Akira
A
Suzuki
Mitsuya
M
D000818:Animals; D003051:Cochlea / Q000187:drug effects* / Q000473:pathology* / Q000503:physiopathology; D005857:Germanium / Q000506:poisoning*; D006168:Guinea Pigs; D034381:Hearing Loss / Q000139:chemically induced* / Q000473:pathology* / Q000503:physiopathology; D008297:Male; D008928:Mitochondria / Q000187:drug effects / Q000473:pathology; D028361:Mitochondrial Diseases / Q000139:chemically induced* / Q000473:pathology* / Q000503:physiopathology
D005857:Germanium; C040516:germanium oxide