Protective effect of Math1 gene & NGFβ gene transfection on cochlear spiral ganglion cells following noise-induced hearing damage

Objective To observe the protective effect of Math1/NGFβ (Mouse atonal homologue Ⅰ gene/ nerve growth factor beta gene) gene transfection on spiral ganglion cells in guinea pigs with noise-induced hearing damage.Methods Forty heahhy white guinea pigs were used to develop the model of stable noiseinduced hearing damage (110 dB SPL).Thirty-five animals with hearing threshold greater than 60 dB SPL both before and after burst explosion were chosen as experimental animals,and then were randomly divided into 4 groups:groups Ⅰ,Ⅱ,Ⅲ and Ⅳ.The animals in group Ⅰ (n =10) (or the Mathl/NGFβ group) were inoculated with Ad-Math1/NGFβ,the animals in group Ⅱ (n =10) or (the Math1 group) were imported with Ad-Mathl,the animals in group Ⅲ(n =10) (or the NGF group) were imported with Ad-NGFβ,the animals in group Ⅳ (or the control group) were imported with adenovirus,and still another 5 healthy white guinea pigs were chosen as the normal group,which had neither noise exposure nor gene transfection.Cochlea sections of guinea pigs were collected for immunohistochemical staining,respectively at week 1 after gene transfection.Then,at week 4 after gene transfection,cochlea sections of guinea pigs were collected for HE staining.Results At week 1 after gene transfection,genes of Ad-Math1/NGFβ were successfully transfected in the cochlea of guinea pigs and expressions of Ad-Math1/NGFβ protein could be detected in each turn of the cochlea,with expression intensity being essentially the same.HE staining at week 4 after gene transfection indicated that the number of spiral ganglions in the Math1/NGFβ group was on the average (166.4 ± 2.58),which was significantly greater than those of group Ⅱ (92.1 ± 1.34) and group Ⅲ (88.6 ± 1.22)),with statistical significance (P ＜ 0.01).Conclusions Ad-Math1/NGFβ could be expressed at a high level in the noiseimpaired cochlea,suggesting that Ad-Math1/NGFβ seemed to have a protective effect on cochlear spiral ganglion cells following noise-impaired hearing damage. Key words: Math 1 gene;  Nerve growth factor gene;  Noise;  Spiral ganglion cells;  Gene therapy