The purpose of this experimental study was to investigate the protective role of intratympanically administered
dexamethasone on the inner ears of rats that were exposed to
streptomycin ototoxicity. Twenty-four adult Wistar albino rats were separated into 4 groups: Group 1 (only
streptomycin), Group 2 (only intratympanic
dexamethasone), Group 3 (
streptomycin and intratympanic
dexamethasone), and Group 4 (
streptomycin and intratympanic saline). All rats were evaluated with distortion product otoacoustic emissions (DPOAE) tests before the start of treatment and on the day it ended. On the 45th day, after the final DPOAE tests, animals of all groups were sacrificed under
general anesthesia. The differences between the amplitudes of DPOAE results were determined, and hearing results were statistically analyzed. Also, the cochleas of each rat were histopathologically evaluated under a light microscope with
hematoxylin and
eosin staining. In the intratympanic
dexamethasone group it was observed that cochlear hair cells were mostly protected. No significant difference was seen between the DPOAE results before and
after treatment (p >0.05). On the other hand, loss was observed in the hearing functions and hair cells of the rats that received
streptomycin and
streptomycin plus intratympanic saline (p <0.05). In the
streptomycin plus intratympanic
dexamethasone group, the cochlear hair cells were partially protected. A significant difference was observed when the DPOAE results (DP-grams) of the
streptomycin plus intratypmanic
dexamethasone group were compared to those of the
streptomycin plus intratympanic saline group (p <0.05). After the experimental study, ototoxic effects of the administration of
streptomycin and intratympanic
dexamethasone were observed on the rats' cochlear hair cells. We conclude that intratympanic
dexamethasone has protective effects against this cochlear damage in rats.