Although cisplatin is a widely used chemotherapeutic agent, it is severely toxic and causes irreversible hearing loss, restricting its application in clinical settings. This study aimed to determine the molecular mechanism underlying cisplatin-induced ototoxicity. Here, we established in vitro and in vivo ototoxicity models of cisplatin-induced hair cell loss, and our results showed that reducing STING levels decreased inflammatory factor expression and hair cell death. In addition, we found that cisplatin-induced mitochondrial dysfunction was accompanied by cytosolic DNA, which may act as a critical linker between the cyclic GMP-AMP synthesis-stimulator of interferon genes (cGAS-STING) pathway and the pathogenesis of cisplatin-induced hearing loss. H-151, a specific inhibitor of STING, reduced hair cell damage and ameliorated the hearing loss caused by cisplatin in vivo. This study underscores the role of cGAS-STING in cisplatin ototoxicity and presents H-151 as a promising therapeutic for hearing loss.
Cisplatin/toxicity* ; Animals ; Nucleotidyltransferases/antagonists & inhibitors* ; Membrane Proteins/antagonists & inhibitors* ; Signal Transduction/drug effects* ; Mice ; Hair Cells, Auditory, Inner/pathology* ; Antineoplastic Agents/toxicity* ; Mice, Inbred C57BL ; Hearing Loss/metabolism* ; Male ; Ototoxicity/metabolism*

Noise-induced hearing loss is a worldwide public health issue that is characterized by temporary or permanent changes in hearing sensitivity. This condition is closely linked to inflammatory responses, and interventions targeting the inflammatory gene tumor necrosis factor-alpha (TNFα) are known to mitigate cochlear noise damage. TNFα-induced proteins (TNFAIPs) are a family of translucent acidic proteins, and TNFAIP6 has a notable association with inflammatory responses. To date, there have been few reports on TNFAIP6 levels in the inner ear. To elucidate the precise mechanism, we generated transgenic mouse models with conditional knockout of Tnfaip6 (Tnfaip6 cKO). Evaluation of hair cell morphology and function revealed no significant differences in hair cell numbers or ribbon synapses between Tnfaip6 cKO and wild-type mice. Moreover, there were no notable variations in hair cell numbers or hearing function in noisy environments. Our results indicate that Tnfaip6 does not have a substantial impact on the auditory system.
Animals ; Mice, Knockout ; Hair Cells, Auditory, Inner/pathology* ; Mice ; Mice, Transgenic ; Hearing Loss, Noise-Induced ; Evoked Potentials, Auditory, Brain Stem/physiology*

BACKGROUND AND OBJECTIVES: The antioxidant ebselen will be able to limit or prevent the ototoxicity arising from 2-hydroxypropyl-β-cyclodextrin (HPβCD). Niemann-Pick Type C (NPC) disease is a disorder of lysosomal storage manifested in sphingolipidosis. Recently, it was noted that experimental use of HPβCD could partially resolve the symptoms in both animals and human patients. Despite its desirable effect, HPβCD can induce hearing loss, which is the only major side effect noted to date. Understanding of the pathophysiology of hearing impairment after administration of HPβCD and further development of preventive methods are essential to reduce the ototoxic side effect. The mechanisms of HPβCD-induced ototoxicity remain unknown, but the resulting pathology bears some resemblance to other ototoxic agents, which involves oxidative stress pathways. To indirectly determine the involvement of oxidative stress in HPβCD-induced ototoxicity, we tested the efficacy of an antioxidant reagent, ebselen, on the extent of inner ear side effects caused by HPβCD. MATERIALS AND METHODS: Ebselen was applied prior to administration of HPβCD in mice. Auditory brainstem response thresholds and otopathology were assessed one week later. Bilateral effects of the drug treatments also were examined. RESULTS: HPβCD-alone resulted in bilateral, severe, and selective loss of outer hair cells from base to apex with an abrupt transition between lesions and intact areas. Ebselen co-treatment did not ameliorate HPβCD-induced hearing loss or alter the resulting histopathology. CONCLUSIONS: The results indirectly suggest that cochlear damage by HPβCD is unrelated to reactive oxygen species formation. However, further research into the mechanism(s) of HPβCD otopathology is necessary.
Animals ; Ear, Inner ; Evoked Potentials, Auditory, Brain Stem ; Hair Cells, Auditory, Outer ; Hearing Loss ; Hearing ; Humans ; Mice ; Oxidative Stress ; Pathology ; Reactive Oxygen Species ; Sphingolipidoses ; Tight Junctions

OBJECTIVE: To establish the stable and efficient hearing damage model by using low dosage of cispla tin, and investigate the mechanism. METHOD: C57 mice were divided into 7 groups (every group, n = 8), the first group was the control group, the others were separately intraperitoneally injected with different dosages of cispla tin for different time. We measured the auditory brainstem response (ABR) of the mice, and obtained the basal coil of organ Corti. We observed the shape of inner hair cells (IHC) by staining AgNO3 and marked otoferlin in the IHC by immunofluorescence,successively sliced by laser confocal microscopy. The RNA fragments were amplified by RT-PCR. RESULT: After cisplatin administration for four days, the thresholds of the ABR improved in 1.5 mg/kg and 3.0 mg/kg group, and compared with the control group, the ABR thresholds improved in each group with ciplatin administration for seven days. With the same dosage, the ABR threshold of the 0.75 mg/kg x 7 d group was higher than 0.75 mg/kg x 4 d group, and there was no time-effect relationship existing in other groups with different dosage. The otoferlin was less expressed 3.0 mg/kg groups than the control group. However, the oto ferlin expressed in the 1.5 mg/kg groups were almost the same as the control group. The alteration of the IHC was observed most remarkablely in 3.0 mg/kg x 7 d group. CONCLUSION Low dosage of cisplatin can impair the hearing, and the expression of otoferlin may involve in the underlying mechanism.
Animals ; Cisplatin ; toxicity ; Cochlea ; drug effects ; metabolism ; pathology ; Hair Cells, Auditory, Inner ; drug effects ; pathology ; Membrane Proteins ; metabolism ; Mice ; Mice, Inbred C57BL

OBJECTIVE: To detect the expression variation of microRNA-183 family in cochlea of animal model characterized by noise-induced deafness at various time points, and to explore the mechanisms responsible for noise-induced deafness. METHOD: Fifty mice were randomly divided into 5 groups. In the experimental group, 40 mice were exposed to 2-4 kHz narrow band noise at 100 dB SPL 6h per day for 3 consecutive days. The rest 10 mice served as the control group without receiving any noise. Auditory brainsterm response (ABR) were examined at the 1st, 7th, 14th and 28th day compaired with the ABR before the experiment,to confirm noise lead to the permanent threshold shift. The pathological damage processes of hair cell were detected by the basilar membrane stretched techniques. Real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) was apply to quantify the expression of microRNA183 family members. Statistical analysis was performed by the SPSS 17.0 software. RESULT: The hearing of mice in the experimental group was significantly less than that in the control group. In the experimental group, the hearing of mice exposed to noise were markedly less when compared with the one exposure to null-noise. The hearing in the 1st day group was least among experimental groups, and the followed one was mice in the 7th day group. No statistical difference were observed between the 14th and 28th day groups (P > 0.05). The results of surface preparation showed that the outer hair cells were chaotic, deformational, and their number decreased is time-dependent. The missing of the outer hair cells occurred mainly in the first and second rows, while the inner hair cells were not pronouncedly missing. The qRT-PCR showed that the expressions of the three genes (miR-183/96/182)in the 1st day and 7th day group with exposure to noise were less than in the control group (P < 0.01), while no significant difference was found between 1st day and 7th day group (P > 0.05). The expressions rised in the 14th day experimental groups, whereas the 28th day group's expressions of the three genes decreased markedly which were more than that in the 1st day and 7th day group (P < 0.01). CONCLUSION After noise exposure for some time, the expressions of miRNA-183 family members have significant changes in animal model with noise-induced deafness, which indicated that the miRNA183 family members may play important roles in the pathogenesis and development of noise-induced deafness.
Animals ; Disease Models, Animal ; Evoked Potentials, Auditory, Brain Stem ; Female ; Hair Cells, Auditory, Inner ; pathology ; Hair Cells, Auditory, Outer ; pathology ; Hearing Loss, Noise-Induced ; metabolism ; pathology ; Male ; Mice ; MicroRNAs ; metabolism

OBJECTIVETo study the effects of Erlong Zuoci Pill (, ELZCP) and its disassembled: prescriptions on gentamicin (GM)-induced ototoxicity model in vitro.

METHODSAfter the spiral organ of cochleae: of newborn mice (postnatal days: 2-3) cultured for 24 h, GM alone or combined with water extracting-alcohol precipitating solution of ELZCP or with its disassembled prescriptions was added. Hair cells were observed under a fluorescence microscope after TRITC-phalloidin staining, and the cochlear hair cell loss rate was calculated by counting the whole cochlear hair cells and analyzed by whole cochlear hair cells analyzing software.

RESULTSGM induced cochlear outer hair cells (OHCs) and inner hair cells (IHCs) injuries in a dose-dependent manner, and they were significantly different as compared with those in the normal control group (P<0.05, P<0.01). ELZCP at the concentration of 0.003-3 mg/mL could decrease the hair cells loss induced by the 0.3 mmol/L GM (P<0.05, P<0.01), the effects was in a dose-dependent manner, and the concentration of 0.3 mg/mL showed the optimal protective effect. For the ELZCP disassembled prescriptions, Liuwei-Dihuang could decrease OHC loss rate than that in the 0.3 mmol/L GM model group (P<0.05), but the OHC loss rate was still higher than that in the ELZCP group (P<0.01), which indicated that the protective effect of hair cells by Liuwei-Dihuang was not better than that of ELZCP. Poria decreased OHC loss rate from 72.1 % +/-3.7 % to 58.8 %+/- 8.2 % (P<0.05).

CONCLUSIONSELZCP could play a role in antagonizing the injury of cochlear hair cells induced by GM ototoxicity,: and its disassembled prescriptions, Liuwei-Dihuang was the main component to protect the cochlear hair cells from GM-induced ototoxicity, and Magnetitum combined with Radix Bupleurui could strengthen the action of the whole prescription; Poria could reduce GM-induced OHC loss.

Animals ; Dose-Response Relationship, Drug ; Drugs, Chinese Herbal ; pharmacology ; Gentamicins ; toxicity ; Hair Cells, Auditory, Inner ; drug effects ; pathology ; Hair Cells, Auditory, Outer ; drug effects ; pathology ; Mice ; Organ of Corti ; drug effects ; pathology ; Prescriptions ; Tablets

OBJECTIVE: To establish a practical model for Wistar rat cochlea organ culturing in vitro, and to observe the growing status in hypoxia of the spiral ganglion cell and nerve fiber. METHOD: We used an in vitro hypoxia model and dissociated cultures of the basal membrane from the cochlea of 3-day-old Wistar rats. And put them in incubator (37 degrees C, 90% N2, 5% CO2, 5% O2) to hypoxia culture for different times. The culture were Immunofluorescence dyed and count the number of the spiral ganglion cell and the cell density in unit area (24 mm x 36 mm), and observe the morph of nerve fiber under the confocal microscope, the results were compared with controls. RESULT: Hypoxia early (6 h) nerve fiber appear edema, spiral ganglion cell didn't change compared with controls; nerve fiber appear break and disintegration and the spiral ganglion cell decrease in 12 hours culturing, and the cell density in unit area had remarkable difference compared with control (P < 0.01). Hypoxia leads to the cell density decrease in a time-dependent manner, the longer of cultures times in hypoxia, the heavier of damage in spiral ganglion cell and nerve fiber. Twelve hours culturing, and the cell density in unit area had remarkable difference compared with control (P < 0.01). Hypoxia leads to the cell density decrease in a time-dependent manner, the longer of cultures times in hypoxia, the heavier of damage in spiral ganglion cell and nerve fiber. CONCLUSION The study findings suggest that hypoxia makes the spiral ganglion cell and nerve fiber damage of culturing in vitro, and nerve fiber more susceptible than spiral ganglion cell for hypoxia.
Animals ; Cell Count ; Cell Survival ; Female ; Hair Cells, Auditory, Inner ; cytology ; pathology ; Hypoxia ; pathology ; In Vitro Techniques ; Male ; Nerve Fibers ; pathology ; Rats ; Rats, Wistar ; Spiral Ganglion ; cytology ; pathology

OBJECTIVETo study the pathological alteration of the cochlear microcirculation and the role of endothelin (ET) in the process of the noise-induced injury of inner ear.

METHODSThirty rats were randomly divided into five groups: control group and 1, 4, 8, 15 d noise exposure groups (115 dB, white noise, 8 h daily). The cilium of hair cell was observed by scanning electron microscope, the cochlear microcirculation was determined by stretched preparation of the stria vascularis. The level of ET in plasma was measured through radio-immunity. The distribution of ET-1, ETA, ETB, in cochlea were detected through immunohistochemistry staining.

RESULTSIn the 4, 8, 15 d group, severe ischemia appeared on the capillary of stria vascularis and the cilium of hair cell displayed significantly disorder. The level of ET in plasma rose temporarily in the 4 d group. ET-1 activity distributed widely in the rat cochlea, there was no significant difference between the control group and the noise exposure groups. ETA expressed in the plasma of the intermediate cells and the capillary walls in the stria vascularis. The control group and the 1 d group showed weak positive staining, while the 4, 8, 15 d groups showed strong positive. The ETB, activity distributed on the endothelial cells of the capillary of stria vascularis and the alteration of the staining intensity was similar to the manifestation of ETA.

CONCLUSIONSSevere disturbance of the cochlear circulation occurred during the course of the noise injury to the inner ear. At the same time, the activity of the ET system of the cochlea stepped up significantly. It coincided with the ischemia of the stria vascularis. These findings suggest that ET may play an important role in the process of the cochlear microcirculation disorder caused by noise.

Animals ; Cochlea ; pathology ; Ear, Inner ; pathology ; Endothelins ; blood ; Hair Cells, Auditory ; pathology ; Hearing Loss, Noise-Induced ; blood ; pathology ; Male ; Microcirculation ; Rats ; Rats, Sprague-Dawley ; Stria Vascularis ; pathology