| Objective:The study was to explore the age-related hearing impairment related to morphology and proteomics in the auditory neuropathway in Wistar rats,through morphological study and proteomics in the auditory cortex and the cochlear nuclei in the three-month-old rats and the eighteen-month-old rats.Methods:①Auditory brainstem response(ABR)was assessed in the three-month-old rats and the eighteen-month-old rats.Cochlear acetycholinesterase staining,Cochlear nuclei and auditory cortex neurons Toluidine blue staining were used in the morphological study.②Two-dimensional gel electrophoresis(2-DE)and Mass spectrometry(MS)were used to detect the difference proteins in the auditory cortex and the cochlear nuclei between the three-month-old rats and the eighteen-month-old rats.③Immunohistochemistry was used to validate the difference proteins.Result:①ABR threshold in the eighteen-month-old rats (33.5±4.12dBSPL)was significantly increased,compared with that in the three-month-old rats(14.5±2.84dBSPL)(P＜0.01).②Cochlear acetycholinesterase staining showed that the density of efferent nerve endings in the basal turn is less 36%in the eighteen-month-old rats relative to the three-month-old rats,and the loss of never endings was found mostly at the second and the third row of outer hair cells.③The number of neurons of the cochlear nuclei in the eighteen-month-old rats were less 24%than the three-month-old rats.However,the distribution of neuron in the auditory cortex was not markedly changed in two groups.④The differences in protein expression in the auditory cortex and the cochlear nuclei between the three-month-old rats and the eighteen-month-old rats were found,by means of identification of protein spots from 2-DE gels. 13 peptide mass fingerprints(PMF)maps were obtained by MALDI-TOF-MS,and Fructose-bisphosphate aldolase C,Gama-aminobutyrate aminotransferase,Endoplasmic reticulum protein 29,Disulfide isomerase associated 3,NAD-dependent deacetylase sirtuin-2,Leucine aminopeptidase 3,Dihydropteridine reductase(with NADH),Ndufa10 protein,glial fibrillary acidic proteins,Cofilin-1,glutamate dehydrogenase [NAD(P)],Dihydrolipoamide dehydrofenase,Nipsnap1protein(Fragment), Glyceradehyde-3-phosphate dehydrogenase were identified.⑤The immunohistochemical study demonstrated that SirT2 expression in the cochlear nuclei of the eighteen-month-old rats were decreased.CONCLUSION:①Auditory neuropathway of the eighteen-month-old rats had been significantly degenerated.②The differences in the protein expression in the auditory cortex and the cochlear nuclei between the three-month-old rats and the eighteen-month-old rats were found,which may be related to age-related heating impairment. |
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