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

OBJECTIVETo study the protective effect of peperphentonamine hydrochloride (PPTA) against gentamicin-induced cochlear damage and its mechanism to inhibit cell apoptosis.

METHODSGuinea pigs with normal hearing were randomized into control, gentamicin, and PPTA treatment groups, and the guinea pigs models of gentamicin-induced cochlear damage received intraperitoneal injection of PPTA. The changes of hearing of the guinea pigs were evaluated with auditory brainstem response (ABR) test, and the protein expression of caspase-3 in the cochlear tissue was detected using Western blotting. TUNEL staining, scanning and transmission electron microscopy were performed to observe the morphological changes of the cochlea.

RESULTSThe threshold in ABR in PPTA treatment group was significantly higher than that in the control group (P<0.05) but significantly lower than that in gentamicin group. Western blotting showed a significantly increased caspase-3 expression in gentamicin group (P<0.001); caspase-3 expression in PPTA group was obviously higher than that in the control group but much lower than that in gentamicin group (P<0.001). TUNEL assay and electron microscopy revealed serious damages of the hair cells in gentamicin group with numerous apoptotic cells in the organ of Corti, stria vascularis and spiral ganglion, and such cochlear damages were obviously alleviated in PPTA group.

CONCLUSIONPPTA can protect against gentamicin-induced cochlear damage in guinea pigs by decreasing the protein expression of caspase-3 to inhibit cell apoptosis.

3,4-Methylenedioxyamphetamine ; analogs & derivatives ; pharmacology ; Animals ; Apoptosis ; drug effects ; Caspase 3 ; metabolism ; Cochlea ; drug effects ; pathology ; Evoked Potentials, Auditory, Brain Stem ; Gentamicins ; adverse effects ; Guinea Pigs

OBJECTIVETo study the protective effect of Ligustrazine Injection (LI) against cisplatin-induced ototoxicity and to explore its mechanism.

METHODSThirty healthy adult guinea pigs were randomly divided into three groups, 10 in each group, i.e., the normal control group, the cisplatin group, and the LI group. Guinea pigs in the normal control group were intraperitoneally injected with normal saline at 3 mL/kg for 7 consecutive days. Those in the cisplatin group were intraperitoneally injected with cisplatin at 3 mg/kg for 7 consecutive days. Those in the LI group were intraperitoneally injected with LI at 140 mg/kg for 7 days, but cisplatin (3 mg/kg) was intraperitoneally injected from the opposite side starting from the 4th day. Brainstem auditory evoked potential (BAEP) was performed in all animals before and after injection. All animals were sacrificed after the final testing under anesthesia and their cochleas collected. Half the cochleas of each group were collected for silver nitrate staining of cochlear basilar membrane stretched. The other half the cochleas of each group made into paraffin sections to observe the apoptosis of cochlea cells by TUNEL method and the expression levels of c-Jun detected by immunohistochemistry.

RESULTSThere was no statistical difference in the difference of BAEP threshold among the 3 groups before injection (P > 0.05), but the BAEP threshold increased in the cisplatin group and the LI group (P < 0.05). Besides, it was higher in the cisplatin group (P < 0.05). In the cisplatin group, most hair cells were missing, spiral ganglion cells obviously decreased, more TUNEL positive cells occurred, and the expression of c-Jun was stronger. But the aforesaid impairment in the LI group was obviously lessened (P < 0.05).

CONCLUSIONSLI showed certain antagonist effect on cisplatin-induced ototoxicity. Its mechanism might be associated with scavenging oxygen radicals of the cochlea tissue, improving the microcirculation, and fighting against apoptosis.

Animals ; Apoptosis ; drug effects ; Cisplatin ; toxicity ; Cochlea ; drug effects ; metabolism ; pathology ; Evoked Potentials, Auditory, Brain Stem ; Guinea Pigs ; Pyrazines ; pharmacology ; Reactive Oxygen Species ; metabolism

The aim of the present study was to assess the ototoxicity of kanamycin sulfate (KM) in adult rats and its underlying mechanism. Forty male Sprague-Dawley rats (6-7 weeks old) were randomly divided into the experimental group and the control group. The animals in the experimental group were injected subcutaneously with KM (500 mg/kg per day) for two weeks, and the control group received equal volume of normal saline. To assess the ototoxicity of KM, the auditory brainstem response (ABR) was recorded to monitor the changes in hearing thresholds, and the density of spiral ganglion cells (SGCs) and morphology of cochlea were observed using surface preparations and frozen sections of cochlea. The results showed that the hearing threshold of rats in the experimental group was elevated by more than 60 dB across all the frequencies two weeks after the first administration of KM. And in the experimental group, the density of SGCs became lower, and organ of Corti suffered loss of hair cells. The loss of outer hair cells (OHCs) was more severe than that of inner hair cells (IHCs), correlated with the density decrease of SGCs. We conclude that the ototoxicity of KM in the adult rats was apparent and the underlying mechanism is associated with the loss of SGCs and hair cells.
Animals ; Cochlea ; drug effects ; pathology ; Evoked Potentials, Auditory, Brain Stem ; drug effects ; Hair Cells, Auditory, Outer ; cytology ; drug effects ; pathology ; Hearing Loss ; chemically induced ; physiopathology ; Kanamycin ; toxicity ; Male ; Random Allocation ; Rats ; Rats, Sprague-Dawley ; Spiral Ganglion ; pathology ; physiology ; ultrastructure

OBJECTIVETo explore the effect of acupuncture at "Neitinggong" drug-induced deafness.

METHODSGuinea pig deafness model was prepared by injection of gentamicin (GM). Acupuncture was respectively given at the points "Neitinggong" "Tinggong" (SI 19) and non-acupoints on the auricle in the experimental animals in different groups and the effects of different points on the auditory brainstem response and cochlear hair cells were observed.

RESULTSThere was a significant difference between GM group and Neitinggong group, and between GM group and Tinggong group. There was no significant difference between GM group and the auricle group, and between Neitinggong group and Tinggong group.

CONCLUSIONAcupuncture at "Neitinggong" can strength the function of the internal ear, and relieve the injury of cochlear hair cells caused by gentamicin, which is an effective acupoint for treatment of drug-induced deafness.

Acupuncture Points ; Acupuncture Therapy ; Animals ; Anti-Bacterial Agents ; toxicity ; Cochlea ; drug effects ; pathology ; Deafness ; chemically induced ; prevention & control ; Evoked Potentials, Auditory, Brain Stem ; drug effects ; Female ; Gentamicins ; toxicity ; Guinea Pigs ; Hair Cells, Auditory ; drug effects ; pathology ; Male

This study was designed to disclose the specific changes of distortion product otoacoustic emission (DPOAE), including DP-gram and I/O-gram in guinea pigs treated with GM for 10 and 17 days. Forty guinea pigs were divided into four groups:group I (treated with GM for 10 days), group II (treated with normal saline for 10 days), group III (treated with GM for 17 days), group IV (treated with normal saline for 17 days). DPOAE including DP-gram and DP-I/O was recorded by use of CELESTA 503 Cochlear Emission Analysis and the out hair cell loss was numerated. (1) The amplitude in group I showed significant reduction at frequencies of 4, 6, 8 kHz. There were significant differences, compared to group II (t=2.52, 1.92, 2.10, P<0.05). The amplitude in group III also decreased at frequencies of 3, 4, 6, 8 kHz. There were also significant differences compared to group IV (t=3.27, 2.81, 2.92, 3.13, P<0.01). The amplitude of DP-I/O in group I and group III at different frequencies and stimulus levels showed reduction. (2) At the level L1 <60 dB SPL, the stimulus levels to elicit a 0 dB response in group I and group III were higher than those in corresponding control groups, respectively. (3) The mean of threshold shift was 5.0+/-3.8 dB in group I and 25.0+/-6 dB in group III at 8 kHz frequency. (4) The out hair cell loss was 22.16% in group I and 48.36% in group III, both showed significant difference as compared to controls, respectively (P<0.01). The employment of DPOAE can be a useful tool in monitoring ototoxicity of GM for its sensitivity and specificity in guinea pigs treated with GM. The changes in DPOAE were consistent with those in histology.
Acoustic Stimulation ; methods ; Animals ; Cochlea ; drug effects ; physiopathology ; Female ; Gentamicins ; administration & dosage ; adverse effects ; Guinea Pigs ; Hair Cells, Auditory, Outer ; drug effects ; pathology ; Male ; Otoacoustic Emissions, Spontaneous ; physiology ; Perceptual Distortion ; drug effects ; physiology ; Random Allocation

To present a summary of current knowledge regarding acute kanamycin sulfate-induced deafness in guinea pig, by reviewing the published literature. Animal model of acute deafness induced by a single dose of kanamycin sulfate in combination with ethacrynic acid or furosemide in guinea pig was usually used to investigate the mechanism of cochlear cell degeneration. There were different time sequences of cell degeneration of spiral ganglion cell and hair cell in different studies. The findings may result from different doses, order of two drugs administration or time point chosen. There remains scope for further research in chronic kanamycin-induced deafness, which more replicates the type of exposure to people than acute deafness.
Animals ; Anti-Bacterial Agents ; administration & dosage ; adverse effects ; Cochlea ; Deafness ; chemically induced ; Disease Models, Animal ; Ethacrynic Acid ; adverse effects ; Guinea Pigs ; Hair Cells, Auditory ; pathology ; Humans ; Kanamycin ; administration & dosage ; adverse effects ; Neurons ; Spiral Ganglion ; drug effects ; pathology

OBJECTIVE: To observe the effects of N-acetyl-L-cysteine (L-NAC) protect hair cells in the rat cochlea from injury of exposure to styrene. METHOD: Seventeen adult Long Evans rats were used in present study. The animals were randomly assigned into test group (n=9) and control group (n=8). The animals were exposed to styrene by gavage at 400 mg/kg (2 g styrene was mixed with 1 ml olive oil). Test group animals received styrene exposure plus L-NAC 325 mg/kg (L-NAC was dissolved in physiological saline solution) by intraperitoneal injection. Treatment was performed once a day, 5 days per week for 3 weeks. Control group animals received the same volume of saline injection on an identical time schedule used for the test group. The auditory brainstem response (ABR) thresholds of both ears elicited with clicks were measured before and at the end of the 3-week styrene or styrene plus L-NAC treatment. After hearing was re-assessed, animals were sacrificed and cochleae were quickly removed from the skull. Following fixation, whole specimens comprising the basilar membrane with Corti's organ were separated from the modiolus. The organs of Corti were stained with propidium iodide (PI) and the TUNEL assay to visualize the morphologic viability of hair cell nuclei, FITC-labeled phalloidin, a F-actin intercalating fluorescent probe used to visualize the morphologic viability of cuticular plate and the stereocilia in the hair cells. Each organ of Corti was thoroughly examined using fluorescence microscopy. The numbers of damaged OHCs (apoptotic, necrotic and missing OHCs) were documented. RESULT: There was a statistically significant decrease in ABR threshold shift (P<0.05) in the styrene-plus-L-NAC treated animals. The average percentage of damaged OHCs in the styrene-treated animals was 28.3%. In contrast, the average percentage of OHC damage in the styrene-plus-L-NAC treated group was only 10.6% (P<0.01). The percentage of reduction in the number of apoptotic cells in styrene-plus-L-NAC treated group was 78% (P<0.01). However, the mean reduction of necrotic cells was only 23% (P>0.05). CONCLUSION The results indicate that the treatment with L-NAC may effectively protect against the styrene-induced hair cells damage and preferably reduce the number of apoptotic OHCs.
Acetylcysteine ; analogs & derivatives ; pharmacology ; Animals ; Antioxidants ; pharmacology ; Cochlea ; cytology ; drug effects ; Evoked Potentials, Auditory, Brain Stem ; Hair Cells, Auditory ; drug effects ; pathology ; Lysine ; analogs & derivatives ; pharmacology ; Rats ; Rats, Long-Evans ; Styrene ; adverse effects

The aim of this study was to determine the effects of transplanted neural differentiated human mesenchymal stem cells (hMSCs) in a guinea pig model of auditory neuropathy. In this study, hMSCs were pretreated with a neural-induction protocol and transplanted into the scala tympani of the guinea pig cochlea 7 days after ouabain injury. A control model was made by injection of Hanks balanced salt solution alone into the scala tympani of the guinea pig cochlea 7 days after ouabain injury. We established the auditory neuropathy guinea pig model using 1 mM ouabain application to the round window niche. After application of ouabain to the round window niche, degeneration of most spiral ganglion neurons (SGNs) without the loss of hair cells within the organ of Corti and increasing the auditory brain responses (ABR) threshold were found. After transplantation of neural differentiated hMSCs, the number of SGNs was increased, and some of the SGNs expressed immunoreactivity with human nuclear antibody under confocal laser scanning microscopy. ABR results showed mild hearing recovery after transplantation. Based on an auditory neuropathy animal model, these findings suggest that it may be possible to replace degenerated SGNs by grafting stem cells into the scala tympani.
Animals ; Cardiotonic Agents/toxicity ; Cochlea/drug effects/pathology ; Disease Models, Animal ; Female ; Guinea Pigs ; Hearing Loss, Central/chemically induced/pathology/*therapy ; Humans ; *Mesenchymal Stem Cell Transplantation ; Mesenchymal Stem Cells/*cytology ; Neurogenesis ; Ouabain/toxicity ; Spiral Ganglion/pathology ; Transplantation, Heterologous

AIMTo study the expression of iNOS and AChE on ginea pigs cochlea spiral ganglion induced by streptomycin (SM) and attenuation by salvia miltiorrhiza injection (Chinese Traditional medicine-dansen DS).

METHODS32 guinea pigs were divided into 4 groups randomly (n=8): control group, SM group, DS + SM group, DS group. SABC immunohistochemical staining and image quantitative analysis technique were used to observe the expression of iNOS and AChE, as well as grey value analysis, and ABR measurements were used to observe ototoxicity.

RESULTSAfter 10 days with drugs, the ABR threshold value of SM increased more significantly than that of the control (P < 0.01), while the ABR threshold value of DS+ SM co-treatment increased than the control group, but lower than that of SM group (P < 0.01). The results of immunohistochemical staining implied the expression of iNOS and AChE in SG of SM group were higher than that of control group, and had positive correlate.

CONCLUSIONThe ABR threshold value increases and the expression of iNOS and AChE strengthen on SM ototoxicity, and has some correlation. DS can attenuate the ototoxicity induced by SM, and has protective function.

Acetylcholinesterase ; metabolism ; Animals ; Cochlea ; drug effects ; metabolism ; Drugs, Chinese Herbal ; pharmacology ; Female ; Guinea Pigs ; Hearing Loss, Sensorineural ; chemically induced ; pathology ; prevention & control ; Male ; Nitric Oxide Synthase Type II ; metabolism ; Protective Agents ; pharmacology ; Random Allocation ; Salvia miltiorrhiza ; chemistry ; Spiral Ganglion ; drug effects ; metabolism ; Streptomycin ; toxicity