Expression Of Cav1.3 Calcium Channel In Inner Ear And Its Correlation With Age Related Hearing Loss

ObjectiveTo investigate the inner ear morphology changes and the expression of CaV1.3 calcium channel in C57BL/6 mice at various ages and study its correlation with age-related hearing loss.MethodsAuditory function were measured with auditory brainstem response (ABR) in C57BL/6 mice at 4,14, 24 and 48weeks. Morphological changes of the inner ear were studied using staining of hematoxylin and eosin (HE) and scanning electron microscopy. The expression of CaV1.3 calcium channel was detected by immunofluorescence and reverse transcription- polymerase chain reaction (RT-PCR).ResultsABR thresholds gradually increased along with age. ABR thresholds at 48 weeks were higher than at 4 weeks (P < 0.01).Morphological examination revealed missing hair cells, missing spiral ganglion cell and lost or disorganized stereocilia in the cochlea with the age increased and hair cells almost absolutely lost at 48 weeks. The number of lost spiral ganglion cells significantly increased and stria vascularis and spiral ligament also had a certain degree of atrophy at 48 weeks. Immunofluorescence photographs reveal that CaV1.3 calcium channel was localized in the lateral wall membrane,apical membrane of the hair cell,stria vascularis,spiral ganglion cell,spiral ligment,spiral prominence(SP),limbus laminae spiralis (LLS), Moderate staining was observed in the vestibular membrane(VM). The expression of CaV1.3 calcium channel gradually decreased as the age increased.The result of RT-PCR inform mRNA of CaV1.3 calcium channel gene(CACNA1D) possess tissue specificity,which were measured in cochlea and kidney and the expression of CACNA1D at aged C57BL/6 mouse was less than adult mouse.ConclusionThe C57BL/6 mouse strain demonstrates clear age-related hearing loss and the inner ear morphology changes. Expression of CaV1.3 calcium channel inner ear of C57BL/6 mouse decreased along with age. This may be related to age-related hearing loss.