Effect Of Different Concentrations Ouabain On Inner Ear Morphology And Hearing Function Of Guizhou Miniature Pig:a Preliminary Study

The Ouabain is an efficient Na+/K+ATP-ase inhibitor which had been used as a drug for treatment of heart failure. In the inner ear, there are distribution of a lot of Na+/K+ATP-ase, which plays an important role in maintaining ion homeostasis and the large cation gradients that exist between the endolymph and the perilymph. Studies have shown that Ouabain can damage the spiral ganglion cells and cause some damage to the hair cells in rats, gerbils and mice experiments. Local application to the gerbil inner ear, the Ouabain resulted in specific damage to spiral ganglion type I element, and thus created an animal model of auditory neuropathy which could be useful for the study of pathogenesis and treatment of auditory neuropathy. In the inner ear of guinea pigs, however, Ouabain mainly damaged the hair cells. In comparison with rodent animals used in the inner ear experiment, the mininature pig is more close to humans in terms of degree of evolution and inner ear size and shape.Objective:To explore the effects of local application of ouabain solution on the inner ear morphology and hearing function of Guizhou miniature pig ear.Method:Through surgical expourse, the ouabain in different concentrations or saline was applicated to the round window niche of Guizhou miniature pig. Annimals were divided into four groups including the1mM group,0.1mM group, normal saline control group and normal control group. Auditory brainstem response(ABR) test and immunohistochemical method were used to evaluate the change of cochlea spiral ganglion, inner ear hair cells and the hearing function after the drug application.Results:Neither the cochlea morphology nor the hearing function in two control groups was apparently changed. In the1mM group and0.1mM group, there was a significant decrease in the amount of spiral ganglion cells with notable elevation in the ABR thresholds. These changes seem more obvious in the1mM group than in the0.1mM group. After two weeks of drug application, inner ear hair cells were found in a disturbance arrangement while without significant loss in the number of hair cells in1mM group. The hair cell morphology and amount were basically normal in animals of0.1mM group.Conclusion:Local application of ouabain solution cause signicant damages to the spiral ganglion cells and hearing function which is related to drug concentration. Damages to the hair cells are relatively weak.