Degenerative Changes of Auditory Functions and Age -related Expression of p-ERK1/2 in the Cochlea of the Senescence Accelerated Mouse / 听力学及言语疾病杂志

ABSTRACT

Objective To investigate degenerative changes of auditory functions and age -related expression of phosphorylated extracellular signal -regulated protein kinases1/2(p-ERK1/2) in the cochlea of the senescence accelerated mouse .Methods The 3 ,5 ,7 months old mice were selected for the study and each group had 6 mice . The 8 kHz tone burst auditory thresholds and age -related expression of p -ERK1/2 in the cochlea were studied in the senescence accelerated mouse/prone 8(SAMP8) at 3 ,5 ,7 months .The expression of p -ERK1/2 was analyzed by the optical density of immunohistochemical staining .Results For the auditory function evaluationThe SAMP 8 developed a progressive hearing loss at 8 kHz which showed an age -related significant increase (P< 0 .05) .The ABR thresholds in 3 ,5 ,7 months old groups in the left ear were 31 .817 ± 1 .228 ,54 .329 ± 1 .459 ,58 .330 ± 1 .252 dB SPL ,respectively .In the right ears ,the ABR threshold were 32 .474 ± 1 .041 ,53 .485 ± 1 .385 ,57 .842 ± 1 .173 dB SPL ,respectively .p-ERK1/2 protein expressed in the cochlea of the SAMP8 throughout the development sta‐ges ,which developed an age-related significant decrease (P<0 .05) .The average optical density of p -ERK1/2 in the spiral ganglion cells in the 3 ,5 ,7 months old mice were 0 .699 7 ± 0 .018 8 ,0 .621 5 ± 0 .014 7 ,0 .575 3 ± 0 .015 5 ,respectively .In the hair cells ,they w ere 0 .651 9 ± 0 .025 2 ,0 .591 2 ± 0 .010 2 ,0 .559 3 ± 0 .006 7 respec‐tively .Conclusion The expression level of p -ERK1/2 protein decreases when the SAMP 8 develops a progressive hearing loss .This indicates that p-ERK1/2 protein probably has relationship with maintaining functional status of the cochlea and the auditory formation .