OBJECTIVE: To learn the influence the gentamycin on C57BL/6J mice hear and cochlear hair cell ribbon synapses CaV1.3 calcium protein amount. To explore the relationship between hear loss and its dosage correlation change and significance. METHOD: The fixed amino glucoside to C57BL/6J mice was used to make abdominal cavity injection mold every day. The auditory brain-stem response ABR was used to measure the hear of mice in 7th, 14th, 28th after the injection. Immunofluorescence method was used to observe cochlear basement membrane of hair ribbon synapse CaV1.3 calcium channel proteins in the distribution and expression. Inner hair cells synaptic membrane was immune fluorescent tags with CtbP2 and CaV1. 3. RESULT: With the growth of the injected drugs, ABR threshold increased,but all the hair cells and shape had no obvious change. However the amount of hair rib bon synapse CaV1.3 calcium ion channel proteins in the expression had significant differences (P < 0.01). CaV1.3 calcium ion channel proteins increased slightly lower than normal at 7th day, significantly decreased at 14th day, had increased, increased quantity compare with 14th day, but at 28th day after intraperitoneal injection of gentamicin. CONCLUSION The increasing,decreasing and increasing trend of cochlear hair cells CaV1.3 proteins in the environment of amino glucoside drug toxicity showed that the increase of hair ribbon synapse CaV1.3 proteins may have a compensatory effect on the drug toxicity. With the increase of the drug toxicity effect, this kind of decompensated function could be the listening decline, which may be one of the mechanism of damage to hearing.
Animals ; Calcium Channels, L-Type ; metabolism ; Evoked Potentials, Auditory, Brain Stem ; Gentamicins ; pharmacology ; Hair Cells, Auditory, Inner ; drug effects ; metabolism ; Mice ; Mice, Inbred C57BL ; Proteomics

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

Hair cells at the base of the cochlea appear to be more susceptible to damage by the aminoglycoside gentamicin than those at the apex. However, the mechanism of base-to-apex gradient ototoxicity by gentamicin remains to be elucidated. We report here that gentamicin caused rodent cochlear hair cell damages in a time- and dose-dependent manner. Hair cells at the basal turn were more vulnerable to gentamicin than those at the apical turn. Gentamicin-conjugated Texas Red (GTTR) uptake was predominant in basal turn hair cells in neonatal rats. Transient receptor potential vanilloid 1 (TRPV1) and 4 (TRPV4) expression was confirmed in the cuticular plate, stereocilia and hair cell body of inner hair cells and outer hair cells. The involvement of TRPV1 and TRPV4 in gentamicin trafficking of hair cells was confirmed by exogenous calcium treatment and TRPV inhibitors, including gadolinium and ruthenium red, which resulted in markedly inhibited GTTR uptake and gentamicin-induced hair cell damage in rodent and zebrafish ototoxic model systems. These results indicate that the cytotoxic vulnerability of cochlear hair cells in the basal turn to gentamicin may depend on effective uptake of the drug, which was, in part, mediated by the TRPV1 and TRPV4 proteins.
Animals ; Cell Death/drug effects ; Cell Polarity/drug effects ; Cell Survival/drug effects ; Dose-Response Relationship, Drug ; Gadolinium/metabolism ; Gentamicins/*metabolism/pharmacology ; Hair Cells, Auditory/drug effects/*metabolism ; Hair Cells, Auditory, Inner/drug effects/metabolism ; Rats ; Rats, Sprague-Dawley ; Ruthenium Red/metabolism ; TRPV Cation Channels/*metabolism ; Time Factors ; Xanthenes/metabolism ; Zebrafish

Objective: The aim of this study was to explore the ototoxicity of toluene in the early development of zebrafish embryos/larvae. Methods: Zebrafish were utilized to explore the ototoxicity of toluene. Locomotion analysis, immunofluorescence, and qPCR were used to understand the phenotypes and molecular mechanisms of toluene ototoxicity. Results: The results demonstrated that at 2 mmol/L, toluene induced zebrafish larvae death at 120 hours post fertilization (hpf) at a rate of 25.79% and inhibited the rate of hatching at 72 hpf. Furthermore, toluene exposure inhibited the distance travelled and average swimming velocity of zebrafish larvae while increasing the frequency of movements. As shown by fluorescence staining of hair cells, toluene inhibited the formation of lateral line neuromasts and middle line 1 (Ml Conclusion This study indicated that toluene may affect the development of both the inner ear and lateral line systems in zebrafish, while the lateral line system may be more sensitive to toluene than the inner ear.
Animals ; Ear, Inner/growth & development* ; Embryo, Nonmammalian/drug effects* ; Gene Expression Regulation, Developmental/drug effects* ; Hair Cells, Auditory/metabolism* ; Lateral Line System/growth & development* ; Locomotion/drug effects* ; Ototoxicity/physiopathology* ; Toluene/toxicity* ; Zebrafish

OBJECTIVETo investigate the effect of D-AP5 (D-2-amino-5-phosphonopentanoate, a specific NMDA-antagonist) on the increase of intracellular free Ca2+ concentration ([Ca2+]i) induced by glutamate in isolated cochlear inner hair cells (IHCs), and to detect the autoreceptors of the IHC membrane.

METHODSWhen a laser scanning confocal microscope (LSCM) was used, the exogenous glutamate (Glu)-induced changes in [Ca2+]i of isolated IHCs and OHCs of guinea pig cochlea were observed with fluo-3, a fluorescent probe for [Ca2+]i. After D-AP5 or CNQX (6--cyano--7--nitroguinoxaline--2, 3--dione, a specific AMPA- antagonist) was administered, the exogenous glutamate (Glu)-induced changes in [Ca2+]i of isolated IHCs were recorded.

RESULTSIn the presence of a low concentration Glu (3.85 mumol/L), there was an increase of [Ca2+]i in IHCs, whereas there was no change in OHCs. When 50 mumol/L of D-AP5 was administrated in advance, Glu did not induce a corresponding increase in [Ca2+]i in IHCs, and 50 mumol/L of CNQX did not completely block the increase of [Ca2+]i in IHCs.

CONCLUSIONSThese results suggest that the autoreceptors existing in the IHC membrane are mainly of NMDA type, while there are relatively few AMPA receptors. Exogenous Glu is capable of increasing [Ca2+]i in IHCs by acting on the NMDA autoreceptor of IHCs in a positive feedback manner.

2-Amino-5-phosphonovalerate ; pharmacology ; 6-Cyano-7-nitroquinoxaline-2,3-dione ; pharmacology ; Animals ; Calcium ; metabolism ; Excitatory Amino Acid Antagonists ; pharmacology ; Glutamic Acid ; pharmacology ; Guinea Pigs ; Hair Cells, Auditory, Inner ; drug effects ; metabolism ; In Vitro Techniques ; Receptors, N-Methyl-D-Aspartate ; antagonists & inhibitors