An Experimental Study On The Expression Of The Heat Shock Protein 70 In Guinea Pigs Cochlea After Cisplatin Ototoxicity

Objective Recent years,following with the research of the heat shock protein70(HSP70),it was found that many hearing lose by a number of different stresses was closely-related with the expression of HSP70.The HSP70 are expressed in normal cells but their expression is enhanced by a number of different stresses including heat and Hyperpyrexia. HSP70 are essential for the survival of cells under an environmental insult. Preparing the animal model of DDP-induced hearing loss and using SP immunohistochemistry method for HSP70 analysis,ABR threshold and latency.The specimens of cochlea were examined by scanning electron microscope.Through observe the effects of the expression of HSP70 after DDP ototoxicity in Cochlea of Guinea Pigs,to study the expression and distributive properties after DDP ototoxicity,to provide theoretical base for clinical prevention and cure.Methods Preparing the animal model of DDP-induced hearing loss.Thirty healthy guinea pigs with normal auricle reflex were used in this study. The animals were divided into three groups.Normal group and DDP groups were subjected to administration of saline and DDP,ip,2.5mg.kg-l.d-l,respectively,and detect the thresholds of ABR and latency every day. The outcome were analyzed statistically.After successive 3 and 6 days respectively,all animals were sacrificed. Cochlea were taken for preparation cochlea section and scanning electron microscope observation. The espression of HSP70 was detected by SP immunohistochemistry method and average gray densities were quantified with a light microscope image analysis sistem.Results The thresholds of ABR were elevated after third and sixth days,and the latency detected were significantly longer.The change of latency as correlated with threshold shift. Under scanning electron microscope,the ciliums of the majority outer hair cells even disappeared in DDP group,while the the ciliums of the majority hair was remained regular and tidy in control group..Hsp70 was present in the control group at a lower level,including Corits organ(outer hair cell inner hair cell Deiter cell Hensen's cell stereocilium) stria vascularis,spiral limbus,spiral ganglion cells.The level of HSP70 immunoreactivity in the guinea pig cochlea of DDP group animal were high,including Corn's organ,stria vascularis,spiral limbus,spiral ganglion cells.especially after successive 6 days. The average gray densities of HSP70 of DDP group animal were significantly different(P<0.01)from the control group.Conclusion DDP can induce the expression of HSP70 in guinea pigs cochlea.