Expression ofα2-Na/K-ATPase in C57BL/6J Mice Inner Ear and Its Relationship with Age-related Hearing Loss

K^(+)cycling in the cochlea is critical to maintain hearing.Many sodium-potassium pumps are proved to participate in K^(+)cycling,such as Na/K-ATPase.Theα2-Na/K-ATPase is an important isoform of Na/K-ATPase.The expression ofα2-Na/K-ATPase in the cochlea is not clear.In this study,we used C57BL/6 mice as a model of presbycusis and implemented immunohistochemistry staining and quantitative real time-PCR,and theα2-Na/K-ATPase expression pattern was confirmed in the inner ear.It was foundα2-Na/K-ATPase was expressed widely in cochlea and its mRNA and protein expression was gradually reduced with aging(4-,14-,26-and 48-weeks old mice).We suspected that,the down-regulation ofα2-Na/K-ATPase expression might be associated with the remodeling of K^(+)cycling,degeneration of morphological structure and decrease of hearing function in aging C57 mice.In conclusion,we speculated that the reduction ofα2-Na/K-ATPase might play an important role in the pathogenesis of age-related hearing loss.

Expression Patterns and Implications of LaminBl in Rat Cochleae

LaminB1,a major component of the nuclear lamina,is a potent regulator of cellular proliferation and senescence and also known to be essential for neuronal migration and brain development.However,the expression patterns of LaminB1 in the rat cochleae are still not fully revealed.Utilizing immunofluorescence.Western blotting,and quantitative real-time PCR,we identified the distribution and expression of LaminB1 in the rat cochleae.Immunofluorescence staining indicated that LaminBl was mainly localized in the auditory hair cells(HCs),spiral ganglion cells(SGC),stria vascularis(STV,including spiral ligament),Reissner's membrane(RM),and limbus laminae spiralis(LLS).Western blotting analysis illustrated that the distribution of LaminBl in rat cochleae was characterized by tissue specificity.The LaminB1 protein was expressed more in SGC and basilar membrane(BM)than in STV.Meanwhile,the mRNA expression of LaminB1 displayed difference in cochlear tissues.These observations preliminarily revealed the expression patterns of LaminB1,providing a theoretical basis for further study on the role of LaminB1 in auditory function.

Comparisons of Supine Roll Test and Alternative Positional Tests in HC-BPPV Lateralization

Objective The purpose of the study was to evaluate the efficiency of the supine roll test(SRT)and alternative positional tests(APTs)including the bow and lean test(BLT),pseudo-spontaneous nystagmus(PSN),and lying down nystagmus(LDN)to identify the affected side in horizontal canal benign paroxysmal positional vertigo(HC-BPPV).Methods In our prospective study,we performed a testing profile(PSN,BLT,LDN,SRT)on 59 HC-BPPV patients using videonystagmography.We compared the accuracy and sensitivity of these tests in HC-BPPV lateralization.Data from 30 healthy patients were collected as the control group.Results When performing positional tests,the elicited nystagmus coinciding with Ewald’s second law was defined as a“positive response”.In 44 patients with geotropic nystagmus,the rates of positive response in LDN,PSN,and BLT were 22/44(50%),19/44(43%),and 18/44(41%),respectively,while in 15 patients with apogeotropic nystagmus,the positive response rates of these three tests were 10/15(66.7%),9/15(60%),and 4/15(27.00%),respectively.The sensitivity of LDN(54.38%)was higher than that of PSN(47.37%)and BLT(38.60%)but lower than that of SRT(89.47%).Notably,the accuracy rate of PSN(71.8%)was higher than that of the other APTs.In 6 patients with symmetrical nysgtamus during the roll test,5 patients showed a positive response in both LDN and BLT(83.34%),whereas 4 patients showed a positive response in PSN(66.67%).Conclusion All positional tests are helpful for determining the affected side of HC-BPPV,but SRT carries the highest accuracy of lateralization followed by PSN.