[Protective effect of NT-3 gene mediated by hydroxyapatite nanoparticle on the cochlea of guinea pigs injured by excitotoxicity].

OBJECTIVE: To transfect the recombinant plasmid enhancement type green fluorescent protein C2- neurotrophic factor-3 (pEGFPC2-NT3) into the spinal ganglion cells(SGCs) of guinea pigs' cochlea injured by the excitotoxicity of hydroxyapatite particle (HAT), to inject the recombinant plasmid pEGFPC2-NT3 into the guinea pigs' cochlea, and to observe the expression of pEGFPC2-NT3 and the protective effect of pEGFPC2-NT3 on SGCs of the cochlea in guinea pigs. METHODS: The recombinant plasmid pEGFPC2-NT3 with gene-green fluorescent protein was established. Kanic acid (KA) was injected into guinea pigs'cochleae and the excitotoxicity model was established. After a week the recombinant plasmid was transferred into SGCs of guinea pigs'cochlea treated with HAT. The following week the expression of NT-3 was examined by the immunohistochemical method, and the morphology of SGNs was observed under the electronic microscope after 4 weeks, in the mean time the changes of auditory brain-stem response (ABR) were examined. RESULTS: The excitotoxicity models were established successfully. NT-3 expression in the intracytoplasm of SGNs was observed by the immunohistochemical method 1 week after the injection, the morphologic damages of SGNs lessened under the electronic microscope after 4 weeks. ABR was partly restored, compared with ABR after the injury of the excitotoxicity. CONCLUSION: On the 7th day, NT3 gene transferred by HAT through the scala tympani can lessen the excitotoxicity of SGCs after KA was injected into the guinea pigs cochlea.