[The expression of miR-183 family in the pathogenesis and development of noise-induced deafness]

To detect the expression variation of microRNA-183 family in cochlea of animal model characterized by noise-induced deafness at various time points, and to explore the mechanisms responsible for noise-induced deafness.

Fifty mice were randomly divided into 5 groups. In the experimental group, 40 mice were exposed to 2-4 kHz narrow band noise at 100 dB SPL 6h per day for 3 consecutive days. The rest 10 mice served as the control group without receiving any noise. Auditory brainsterm response (ABR) were examined at the 1st, 7th, 14th and 28th day compaired with the ABR before the experiment,to confirm noise lead to the permanent threshold shift. The pathological damage processes of hair cell were detected by the basilar membrane stretched techniques. Real-time reverse transcriptase-polymerase chain reaction (qRT-PCR) was apply to quantify the expression of microRNA183 family members. Statistical analysis was performed by the SPSS 17.0 software.

The hearing of mice in the experimental group was significantly less than that in the control group. In the experimental group, the hearing of mice exposed to noise were markedly less when compared with the one exposure to null-noise. The hearing in the 1st day group was least among experimental groups, and the followed one was mice in the 7th day group. No statistical difference were observed between the 14th and 28th day groups (P > 0.05). The results of surface preparation showed that the outer hair cells were chaotic, deformational, and their number decreased is time-dependent. The missing of the outer hair cells occurred mainly in the first and second rows, while the inner hair cells were not pronouncedly missing. The qRT-PCR showed that the expressions of the three genes (miR-183/96/182)in the 1st day and 7th day group with exposure to noise were less than in the control group (P < 0.01), while no significant difference was found between 1st day and 7th day group (P > 0.05). The expressions rised in the 14th day experimental groups, whereas the 28th day group's expressions of the three genes decreased markedly which were more than that in the 1st day and 7th day group (P < 0.01).

After noise exposure for some time, the expressions of miRNA-183 family members have significant changes in animal model with noise-induced deafness, which indicated that the miRNA183 family members may play important roles in the pathogenesis and development of noise-induced deafness.