The Research Of The Relationship Between EPCS And The Damage Of Cochlea In Noise-induced Hearing Loss

Objective:1、The SD rats are identified as the model of noise induced hearing loss. The research platform of inner ear damage and repair is built so as to investigate and observe the change of hearing function and the damage of hair cell in cochlear.2、Through the observation of EPCs in peripheral blood and the express of VEGF, iNOS after noise exposure, we illustrate the pathologic mechanism of cochlear damage and recovery in NIHL.3、We discuss how to prevent and heal the damage of cochlear in NIHL through influence the EPCs.Methods:SD rats are exposed in118±1dBSPL white noise for4hours and established as the model of NIHL. SD rats are divided randomly into5groups according to the time after noise expose, respectively0day group,1day group,3days group,7days group and14days group. The number of rats are10rats every group. The experiment is divided two parts, one part is carried out by only noise; the other part is carried out by influence on the EPCs in body in addition to noise expose. According to the different group and time, hear threshold is measured by ABR. Monoculear cells can be given by Fercoll gradient centrifugation. We observe VEGF、iNOS and CD34by western blot and immunohistochemisty,and observe the cochlear after noise by scanning electron microscope. Adult male SD rats were divided into groups:(1) saline control group,(2) EPO group and (3)cysteine group. We show the different ABR threshold between the different time after noise. Results:1. The hearing threshold is highest in0day group, the number is86.67±6.85dBSPL. The period lies in TTS. The hearing threshold may partly recover in7day group and14day group, the threshold is lower than o day group. The period lies in PTS. The number of hearing threshold is56.18±5.29dBSPL and57.92±6.20dBSPL respectively;2.through the observation of the number of the EPCs in peripheral blood among the several groups, The number of EPCs attains the max in1day group. The number is91.40±8.13/200*103single nucleolus cells. And the number of the EPCs in peripheral blood restore to the normal level in14day group,29.00±14.56/200*103single nucleolus cells;3、In western blot and immunohistochemisty, the max express of VEGF and iNOS occur in1day group and the min express occur inO day group. However, the express of CD34get the highest in3day and7day after noise exposed.4. Through interfering the EPCs, the protection of hearing in EPO group is better than cysteine group. In the process of inner ear recovery, EPCs can advance the angiogenesis and improve the micro-environmental inner ear in cochlear.Conclusion:1. NIHL can result in the damage of cochlear.2. VEGF and iNOS take part in the whole process in NIHL, VEGF and EPCs play a role in different stages in the restoration of cochlear blood vessel after noise damage.3. EPCs plays a very important role in the process of cochlear damage and restoration.