The Expression of Ephrin A2 during the Reinnervation and the Regeneration of the Hair Cells in the Chick Cochlea following Kanamycin Ototoxicity / 听力学及言语疾病杂志

ABSTRACT

Objective To investigate the role of Ephrin A2 in the regeneration and reinnervation of hair cells in the chick cochlea following kanamycin ototoxicity.Methods 66 newly hatched Roman chickens (3 days old) were randomly divided into experimental group and control groups. Experimental chickens (n=48) received intramuscular kanamycin (200 mg/kgSigma,St Louis,MO) for 10 consecutive days and were subsequently sacrificed 2 days before the last injection,and 1,3,7,10,15,21,30,and 60 days after the last injection (n=6 per subgroup). Control chickens (n=18) were untreated and sacrificed 3,13 and 43 days after hatching (n=6 per subgroup). Ephrin A2 protein expression in acoustic ganglia was determined by western blot analysis in all chickens after sacrifice. Results Ephrin A2 protein expression was found and the protein level was almost same in acoustical ganglia of all normal chickens. After kanamycin exposure,the Ephrin A2 protein expression level in the cochlea of the experiment chickens from 2 to 7 days after last kanamycin injection was lower than that in control chickens,respectively. Ephrin A2 expression increased obviously at 15 days after kanamycin last injection. By 30 days after the cessation of kanamycin treatment,the level of Ephrin A2 protein approximated to that in normal control group.Conclusion The expression of Ephrin A2 protein in the acoustical ganglia basically synchronizes with the regeneration and the reinnervation of the hair cells in the chicken cochlea following kanamycin damage,indicating that Ephrin A2 may play an important role in this process.