Quercetine attenuates the gentamicin-induced ototoxicity in a rat model.

OBJECTIVES: The aim of this study is to evaluate the protective role of quercetin in gentamicin-induced ototoxicity through an auditory brainstem response (ABR) test and a histopathological evaluation of the cochlea. METHODS: In this study, 48 female adult Sprague-Dawley rats aged 20-22 weeks and weighing 200-250g were used. An ABR test was carried out on all rats prior to drug administration, after which, the rats were divided into four groups of 12 animals each. Drug administration was gentamicin 120mg/kg plus ethanol in group one; gentamicin 120mg/kg plus quercetin 15mg/kg in group two; quercetin 15mg/kg in group three; and ethanol in group four. The drugs were administered intraperitoneally once a day for two weeks, and the ABR test was repeated after drug administration. Subsequently, the rats were sacrificed and their cochleae were dissected and examined histopathologically. RESULTS: There was no significant difference between the pre-treatment ABR measurement values of the groups. However, a significant increase was detected in the ABR values in the group of rats that were administered gentamicin plus ethanol, while no statistically significant increase was found in the ABR values in the groups administered with gentamicin plus quercetin; quercetin alone; and ethanol alone. The number of TUNEL positive cells in the inner and outer hair cells in the Corti organ was found to be fewer, and Caspase 3 and 9 expressions were found to be weaker in the group receiving gentamicin plus quercetin than in the group receiving gentamicin plus ethanol. CONCLUSIONS: Auditory function was detected to be significantly protected and apoptotic cells were found to be decreased when quercetin was administered together with gentamicin. From these results it was concluded that quercetin, a powerful antioxidant, attenuates ABR thresholds and histopathological lesions in the cochlea in gentamicin-induced ototoxicity in rats.

N-acetylcysteine Prevents Gentamicin Ototoxicity in a Rat Model.

OBJECTIVE: The possible preventive effect of N-acetylcysteine (NAC) in gentamicin ototoxicity was studied with auditory brain stem responses (ABRs), otoacoustic emissions (OAEs), and histopathological investigation of the cochlea. MATERIALS AND METHODS: This study is conducted on 36 rats in three groups. Gentamicin, gentamicin plus NAC, and NAC alone were intraperitoneally administered for 15 days. The rats were sacrificed to study the cochleas after testing hearing levels. RESULTS: ABR thresholds and OAEs were attenuated in the gentamicin group, in which apoptosis was detected with histopathological investigation. The group that received NAC in addition to gentamicin had better ABR thresholds and better OAEs. The histopathological evidence of apoptosis in was considerably less in this group. CONCLUSION: Gentamicin ototoxicity can be detected by ABR and OAE testing in rats, and NAC may protect the cochlear cells from apoptosis.

Cervical and ocular vestibular evoked myogenic potentials in Behcet's disease.

OBJECTIVE: To investigate vestibular evoked myogenic potentials combined with audiologic status in Behcet's disease (BD) and to compare the results with normal healthy subjects. METHODS: Cervical vestibular evoked myogenic potential (cVEMP) test, ocular vestibular evoked myogenic potential (oVEMP) test, Dix-Hallpike test, conventional pure tone audiometry (cPTA) and high frequency audiometry (HFA), and 226 and 1000Hz tympanometry were performed to each subject of the study. Cranial magnetic resonance imaging (MRI) with contrast enhancement was also performed to evaluate the central nervous system (CNS) in patients with BD. RESULTS: VEMP parameters including the mean peak latencies of p13-n23 and n10-p15, AR values and thresholds were not statistically different both in cVEMP and oVEMP between the BD and control groups. Except for 250Hz, mean audiological thresholds were significantly higher in the BD group. Five of the 20 patients had pathological cranial MRI findings that may be compatible with central nervous system involvement. CONCLUSION: To our knowledge, the present study is the first report investigating oVEMP and cVEMP responses combined with MRI findings in patients with BD. The presence of high frequency hearing loss is a common finding in BD and HFA may help early detection of hearing loss in patients with BD when combined with cPTA.

The protective role of thymoquinone in the prevention of gentamicin ototoxicity.

OBJECTIVE: To investigate the potential protective effect of thymoquinone in gentamicin-induced ototoxicity through auditory brain stem responses (ABR) testing and histomorphological evaluation of the cochlea. METHODS: This study was conducted on 48 adult female Sprague-Dawley rats that were randomized into 4 groups. Group 1 received intraperitoneal gentamicin; group 2 received intraperitoneal gentamicin plus corn oil solution; group 3 received intraperitoneal thymoquinone; and group 4 received intraperitoneal gentamicin plus thymoquinone. All groups received the drugs (once daily) in the above-mentioned protocols over 15 days. After conducting repeated ABR measurements, the rats were sacrificed, and their cochleae were isolated. RESULTS: ABR thresholds were preserved in the gentamicin plus thymoquinone group when compared with the group receiving gentamicin alone. There were fewer TUNEL-positive cells and caspase-3 and caspase-9 expressions were weaker in the inner and outer hairy cells of the organ of Corti in the gentamicin plus thymoquinone group compared with the group receiving gentamicin alone. CONCLUSION: The ABR values and number of apoptotic cells did not significantly increase in the group receiving gentamicin plus thymoquinone when compared to the group receiving gentamicin alone. Again, the cochlear histomorphological findings were supportive of the auditory findings. In light of these findings, we conclude that gentamicin-induced ototoxicity may be prevented by thymoquinone use in rats.

The ototoxic effect of intratympanic terbinafine applied in the middle ear of rats.

BACKGROUND: Otomycosis is defined as an infection of the external ear canal with fungal agents. The treatment of the disease is cleansing and drying of the external ear canal, identification and treatment of any predisposing factors and application of topical antifungal agents. Terbinafine is used as an antifungal agent to treat otomycosis. We proposed to investigate the probable ototoxic effect of terbinafine solution on auditory brain stem response (ABR) and distortion product otoacoustic emission (DPOAE) when applied intratympanically in the middle ear of rats. METHODS: The experiment was performed on 30 female Wistar albino rats. Thirty animals were divided into three groups of 10 animals each. 1% terbinafine solution was administered to the first group (group T). The second group (group G) was administered 40 mg/ml gentamicin solution (ototoxic control). The third group (group S) was administered saline solution (negative control). Baseline DPOAE measurements and ABR testing from the left ears were obtained from the animals in all groups under general anesthesia. Ear solutions were applied in the middle ear intratympanically with a dental needle. Treatment was initiated after baseline measurements and repeated once every two days for fifteen days. RESULTS: Pre and post-treatment DPOAE responses for all tested frequencies of group T and Group S showed no statistically significant difference. However, the group G demonstrated a significant change in ABR thresholds and DPOAE responses. CONCLUSIONS: Terbinafine solution is a broad spectrum antifungal agent effective in the treatment of otomycosis. The present study demonstrated that its direct administration in the middle ear of rats does not affect inner ear function as measured by ABR and DPOAE responses.

Protective effect of thymoquinone against cisplatin-induced ototoxicity.

The aim of this study was to investigate the potential protective effect of thymoquinone against cisplatin-induced ototoxicity. This study is a prospective, controlled experimental animal study. Experiments were performed on 30 healthy female Sprague-Dawley rats. Thirty animals were divided into three groups of 10 animals each. Group 1 received an intraperitoneal (i.p.) injection of cisplatin 15 mg/kg. Group 2 received i.p. thymoquinone 40 mg/kg/day for 2 days prior to cisplatin injection and third day i.p. cisplatin 15 mg/kg was administered concomitantly. Group 2 continued to receive i.p. thymoquinone until fifth day. Group 3 received i.p. thymoquinone 40 mg/kg/day for 5 days. Pretreatment distortion product otoacoustic emissions (DPOAE) and auditory brain stem responses (ABR) testing from both ears were obtained from the animals in all groups. After the baseline measurements, drugs were injected intraperitonally. After an observation period of 3 days, DPOAE measurements and ABR testing were obtained again and compared with the pretreatment values. There was no statistically significant difference between pre and post-treatment DPOAE responses and ABR thresholds group 2 and 3. However, group 1 demonstrated significant deterioration of the ABR thresholds and DPOAE responses. Our results suggest that DPOAE responses and ABR thresholds were preserved in the cisplatin plus TQ-treated group when compared with the group receiving cisplatin alone. According to these results, cisplatin-induced ototoxicity may be prevented by thymoquinone use in rats.