Two Different Administration Methods Of Dexamethasone Protect Against Gentamicin Ototoxicity.

Objective: To observe the protection effects of two different administration methods on dexamethasone against gentamicin ototoxicity in the guinea pigs. The study aims at providing experimental evidence for preventing and treating gentamicin ototoxicity in clinical .Methods: 60 guinea pigs were divided into four groups randomly and 15 in each group. (1)GM group: only treated with gentamicin (i.m., 120mg*kg-1*d-1) for 10 days. (2)GM-S-Dex group: treated with gentamicin (the same as GM group) and intraperitoneal injection dexamethasone (2.5mg*kg-1*d-1) simultaneously for 10 days. (3)GM-T-Dex group: treated with gentamicin (the same as GM group) and topically applied of dexamethasone through an intact RWM on right ear for one time. (4)NS-T-Dex group: treated with sodium chloride(i.m., the same volume as gentamicin) for 10 days and topically applied of dexamethasone through an intact RWM on right ear for one time. auditory brainstem response(ABR) was measured before and 1st day,10th day after treatment. All the guinea pigs were killed at the end of the experiment at once , the middle ear mucosa was observed simultaneously. The Corti organ was observed by the scanning electron microscope(SEM).Results: The ABR threshold was raising in the GM group,the GM-S-Dex group and the GM-T-Dex group after treatment(P<0.05). The latency of waveâ…¢(80dB) was prolonging also after treatment. At 10th days after treatment, the ABR threshold of the GM group raised compared with the GM-T-Dex group(P<0.05). The latency of waveâ…¢(threshold) was shorting in the GM group after treatment (P<0.01). At 10th days after treatment, the latency of waveâ…¢(threshold) in the GM group demonstrated shorter than the other groups...