Relationship between the miR-96 expression in the cochlea and ABR threshold and cochlear morphology of BALB/c mice / 中国耳鼻咽喉头颈外科

ABSTRACT

OBJECTIVE Through researching the ABR threshold, the cochlear morphology and miR-96 expression in the cochlear of BALB/c mice at different month's age, to find out if the miR-96 can regulate the age related hearing loss of BALB/c mice.METHODS ABR testing, AO/PI staining and scanning electron microscope were used to observe the ABR threshold and cochlear morphology of the BALB/c mice at the ages of 3 months, 6 months, 12 months and 18 months. Real-time PCR was used to detect the expression of miR-96 in the cochlea of BALB/c mice at the ages of 3 months, 6 months, 12 months and 18 months.RESULTS The ABR thresholds of BALB/c mice were (18.5±8.3), (45.8±7.8), and (85.6±15.6) dB SPL separately at the age of 3, 6 and 12 months. At the age of 18 months, no response was observed in the ABR testing with 120 dB SPL acoustic stimulation. In the AO/PI staining, we found that the outer hair cells was apparently lost since the age of 6 months and the loss of hair cells aggravated as the month's age increased. At the age of 12 months, no outer hair cells was left, inner hair cells was lost apparently too. With the scanning electron microscope, we found the changes of deficiency, lodging, fusion, shortening and inversion in the hair cell cilia. And these changes were aggravated as the month's ages increased. At the age of 3 months, the relative expression of miR-96 (2-△CT) was 0.0225±0.0073. The relative expression of miR-96 (2-△CT) in the cochlea were 0.0162±0.0048, 0.0116±0.0048, and 0.0050±0.0014 at the age of 6 months, 12 months and 18 months separately, comparing with the relative expression of miR-96 at the age of 3 months, the differences were significant(P<0.05).CONCLUSION The hearing loss, hair cells loss, and cilia damage aggravated as the month's age increased, but the miR-96 expression in the cochlea decreased. Which suggest that miR-96 might play an important role in the age related hearing loss.