| Objective:To investigate the effects of mitophagy and glucose metabolism on the ageing process of cochlear nucleus,and whether electroacupuncture at Tinggong and Yifeng delay the ageing process by regulating the mitophagy and glucose metabolism in guinea pig with age-related hearing loss(AHL).Methods: 1.Thirty healthy guinea pigs(4 months old)were randomly divided into three groups,including D-galactose group(DG,n=10),D-galactose and electroacupuncture group(DEG,n=10),and control group(CG,n=10).Guinea pigs received D-galactose(300mg/kg/day)treatment by subcutaneous injection for 6 weeks in DEG and DG,and were electroacupunctured at Tinggong and Yifeng after D-galactose treatment half an hour later in DEG.Moreover,the CG received 0.9% normal saline with the equal volume of D-galactose.Ten elderly guinea pigs(18 months old)in elderly group(EG,n=10)were fed naturally.2.Glucose metabolism was detected in cochlear nucleus by micro PET/CT.3.Quantitative real-time PCR was used to analyze the mRNA levels of LC3,PINK1 and PARK2.The protein expression levels of PINK1 and Parkin were detected in the cochlear nucleus by Western blot.4.Statistical analysis.The statistical analysis was performed using SPSS 24.0 software.The data were expressed as the mean ± standard deviation.Comparisons between multiple groups were performed by one-way ANOVA,and values with P<0.05 were considered significant.Results: 1.There was a statistically difference in the mean ratio of maximum standardized uptake values between the cochlear nucleus and cerebellum in all groups(F=12.143,P=0.001).CG show higher mean ratio than EG and DG(P<0.05),significant difference was not found between DG and EG(P>0.05).In addition,there was a significant increase in the DEG(compared with the DG,P<0.05).2.The mRNA levels of PINK1,PARK2 and LC3 in four groups were significantly different(F=21.614,20.662 and 13.198 respectively for PINK1,PARK2 and LC3,P<0.001).There was a significant increase of the mRNA levels in DG and EG(compared with the CG,P<0.05),decrease in the DEG(compared with the DG,P<0.05),and no statistical difference between DG and EG(P>0.05).3.The protein expressions of PINK1 and PARK2 in four groups were significantly different(F=47.484 and 19.789 respectively for PINK1 and Parkin,P<0.001).Two protein expressions upregulated in DG and EG(compared with the CG,P<0.05),and downregulated in DEG(compared with the DG,P<0.05).At the same time,there were no statistical differences between EG and DG(P>0.05).Conclusions: 1.Decrease of glucose metabolism promote the ageing process of cochlear nucleus in guinea pigs with AHL.2.The early plasticity of cochlear nucleus may be related to PINK1/Parkin-mediated mitophagy in the aging process of guinea pigs with AHL.3.Electroacupuncture at Tinggong and Yifeng can delay the aging process of the cochlear nucleus in guinea pigs with D-galactose-induced AHL by increasing the level of glucose metabolism,and promoting the recovery of PINK1/Parkin-mediated mitophagy. |
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