The Protective Effect Of The Mixture Of BDNF And NT-3 On The Damaged Spiral Ganglion Cells

Objectives:On the basis of establishing animal model of selectivity damaged spiral ganglion cells(SGCs),we investigate the protective effect of brain-derived neurotrophic factor(BDNF), neurotrophin-3(NT-3) and the mixture of them on the SGCs treated with ouabain. Then we Compare the similarities and differences between them, find the main site of the impacted cells in the cochlea and observe the change of cell density, shape and its influence on the organelles. we may provide the basis for clinical work to find the drugs of protecting SGCs.Methods:30 male Mongolian gerbils were randomly divided into four groups:A, B, C, D.The left round window membranes of Mongolian gerbil of Group A were instilled with artificial perilymphatic fluid (APF),and the right ones were instilled with ouabain (80umol/L) to establish animal model of selectivity damaged SGCs. On the basis of ouabain,the left and right round window membranes of Mongolian gerbil of Group B,C,D were instilled with APF or BDNFor NT-3 or the mixture of BDNF and NT-3.We removed the cochlea after 7 days and prepared specimens. Histopathological changes of SGCs were observed by HE staining, and the density of SGCs was calculated. Then semi-quantitative analysis of SGCs density were measured by Image-pro plus6.0.All the dates were analysised by SPSS 17.0, Differences associated with P values of<0.05 were considered as statistically significant. We used the transmission electron microscope (TEM) to observe the ultramicrostructure of the SGCs.Results:SGCs morphology change and organelles damage is more obvious compared with APF group.BDNF, NT-3 and their mixture could rival the ototoxicity of ouabain in the cochlea. When comparing the SGCs density of the same Rosenthal district of D1 group (ouabain-APF group) and D2 group (ouabain-BDNF & NT-3 group),we find the P values are less than 0.05. The difference was statistically significant, and the D1<D2. The morphology of SGCs of the ouabain-BDNF & NT-3 group was more intact than the ouabain-BDNF group or ouabain-NT-3 group.Conclusions:Instilling 80μmol/L ouabain on the round window membranes of Mongolian gerbil could damage the SGCs and its nerve fiber.The Cell body swelled or shrinked,cytoplasm vacuolated, cell nucleus shrinked or dissolved, neurite shortened or fractured, the myelin sheath of medullated fibers dissolved or vacuolated.The protective effect of the mixture on damaged SGCs is more obvious than BDNF or NT-3.