The Experimental Study on the Changes of Hearing Function and Cochlear Morphology in Rat Diffuse Brain Injury Model / 听力学及言语疾病杂志

ABSTRACT

Objective To study the changes of hearing function and cochlear morphology on diffuse brain in-jury model in rat .Methods One hundred and fifty SD rats with normal hearing were randomly divided into five groups ,each group consisted of 30 SD rats ,including a control group and four experimental groups which endured diffuse brain injury(DBI) from one to four weeks .Diffuse brain injury model of rats were established ,then ABR , 40 Hz AERP and ASSR examination ,light microscopy ,electron microscopy were used to evaluate the change of hearing function and morphology .Results The difference of ABR ,40 Hz AERP and ASSR thresholds between the experimental and the normal control group were significant (P<0 .05) .The thresholds of ABR ,40HzAERP and AS-SR were increased in the first week of DBI ,then the threshold continuously increased in the second and third week , at last the threshold decreased in the fourth week .The results under scaning electron microscope demonstrated that the ciliums of the majority of outer hair cells lodged in the first week of DBI .The results under transmission electron microscope showed that in the first week of DBI ,there were edema and denuration of mitochondrial ,mitochondrial cristaes were obscured or disappeared .The changes were deteriorate in the second and third week ,whereas the changes were mitigatal in the fourth week .Conclusion Cochlear morphology and hearing damage were observed in diffuse brain injury model of rats .