Direct inner ear infusion of dexamethasone attenuates noise-induced trauma in guinea pig.
The protective effect of dexamethasone (DEX) against noise-induced trauma, as reflected in hair cell destruction and elevation in auditory brainstem response (ABR) sensitivity, was assessed in guinea pigs. The animals were administered DEX (1, 10, 100, and 1000 ng/ml) or artificial perilymph (AP) via a mini-osmotic pump directly into scala tympani and, on the fourth day after pump implantation, exposed to 120 dB SPL octave band noise, centered at 4 kHz, for 24 h. Animals receiving DEX demonstrated a dose-dependent reduction in noise-induced outer hair cell loss (significant at 1, 10 and 100 ng/ml DEX animals compared to AP control animals) and a similar attenuation of the noise-induced ABR threshold shifts, observed 7 days following exposure (significant at 100 ng/ml DEX animals compared to AP control animals). These physiological and morphological results indicate that direct infusion of DEX into the perilymphatic space has protective effects against noise-induced trauma in the guinea pig cochlea.
Department of Otolaryngology, Kansai Medical University, Fumizono-cho 10-15, Moriguchi, Osaka 570-8507, Japan. takemura@takii.kmu.ac.jp
Keiji
K
Takemura
Mototane
M
Komeda
Masao
M
Yagi
Chiemi
C
Himeno
Masahiko
M
Izumikawa
Tadashi
T
Doi
Hiromichi
H
Kuriyama
Josef M
JM
Miller
Toshio
T
Yamashita
D000818:Animals; D002470:Cell Survival / Q000187:drug effects; D003907:Dexamethasone / Q000008:administration & dosage* / Q000494:pharmacology; D007758:Ear, Inner; D016057:Evoked Potentials, Auditory, Brain Stem / Q000187:drug effects; D005938:Glucocorticoids / Q000008:administration & dosage* / Q000494:pharmacology; D006168:Guinea Pigs; D018072:Hair Cells, Auditory, Outer / Q000187:drug effects / Q000473:pathology; D006317:Hearing Loss, Noise-Induced / Q000473:pathology / Q000517:prevention & control*; D007260:Infusion Pumps; D008297:Male; D012533:Scala Tympani
D005938:Glucocorticoids; D003907:Dexamethasone