[Impact of auditory deprivation on rats and plasticity expressionof growth associated protein-43 in auditory cortex]

Objective:To explore the molecular mechanism of neural plasticity in the reconstitution following impairment of auditory system,we studied the changing levels of GAP-43 expression in the auditory cortex(AC) in the developing rats and in ototoxicity deafened rats before and after electrical intracochlear stimulation.Method:Auditory brain stem response(ABR) measurements were performed to rats of OAD,NC1,CAD and NC2 group to evaluate hearing function.We studied the changing levels of GAP-43-positive neurons expression in the auditory cortex of the OAD,NC1,EIS1 and EIS2 group and RT-PCR was performed to do semiquantitative analysis.Result:The early electrical intracochlear stimulation elevated GAP-43 level(EIS1,120.00±5.59/HP) in ipsilateral AC instead of in the contralateral AC compared with the non-stimulation group (OAD4W,93.25±4.30/HP),and the two groups had statistical difference(EIS1/OAD4W,129.17%±3.33%,P<0.05).After the late electrical intracochlear stimulation,similar to the early group,the staining level of GAP-43(EIS2,102.50±4.02/HP) in the AC was also higher than the unaffected group(OAD8W,81.67±3.76/HP),and the two groups also had statistical difference(EIS2/OAD8W,123.74%±2.70%,P<0.05).Similarly,the expression of GAP-43 mRNA had the synchronous change with the GAP-43 in the AC.Conclusion:GAP-43 has close correlation with the growth and plasticity of the AC,which can be a significant marker for auditory plasticity.