[Effects of exogenous brain-derived neurotrophic factor on the morphology and function of cochlea in the animal model of hereditary hearing loss].

Objective:To study the effect of early administration exogenous BDNF on the morphology and function of conditional knockout Cx26 mice cochlea.Method:Conditional knockout Cx26 mice was chosen as animal model, early after birth (P0-P2) exogenous BDNF (rAAV mediated BDNF plasmid, AAV-BDNF) was injected through scala media. Expression of BDNF in the cochlea was observed by western-blot, the growth promoting effect of nerve fibers was detected by IHC; 2 m after injection, the protective effect of BDNF on corti and spiral ganglion cells were detected by resin section; animal hearing were tested by ABR.Result:①Exogenous BDNF could be well expressed in the inner ear; ②Exogenous BDNF has a good effect on the growth of cochlea nerve fiber; ③Exogenous BDNF could protect the morphology of organ of corti; to count the number of spiral ganglion cells, using the density value of top-turn in non-injected ear as the standard unit, the values of middle and basal turn in injected ear were 0.81±0.02, 0.65±0.02, compared with non-injected ears, both statistically significant difference could be found, indicates that exogenous BDNF can effectively improve the number of spiral ganglion cells. ④By calculating the ABR threshold of different frequencies of the injected and non-injected ear, there was no statistical difference between them. Indicates that exogenous BDNF has no effect on improving the function of cochlea.Conclusion:The protective effect of early administration exogenous BDNF was effective in the cochlea and spiral ganglion cells of conditional knockout Cx26 mice, but no protective effect for auditory function.