Expression of Growth Associated Protein 43 in Inferior Colliculus of Rats at Different Times after Impulse Noise Exposur / 听力学及言语疾病杂志

ABSTRACT

Objective To investigate the effect of impulse noise expose on the expression of growth associated protein 43(Gap-43) in inferior colliculus in rat.Methods SPF grade Male SD rats were randomly divided into 5 groups.The normal control group received noise exposure.The model groups received an averange impulse noise exposure of 156 dB SPL with a pulse duration of 0.23 ms, once for 6 s, for 50 times.Auditory brainstem responses (ABRs) were measured before and 3,7,14, and 28 d after noise exposure with tone pips of 2,4,8,16, and 32 kHz, from 20 to 110 dB SPL.Bilateral inferior colliculus of rats in the model groups was collected and treated by immunohistochemical staining.Gap-43 expression of rats in different groups was measured by determining the gray value of inferior immunohistochemical images.Results After noise exposure, ABRs threshold in the model groups were significantly higher than those of in the normal group (P<0.05 or P<0.01).ABRs threshold at 14 and 28 days after noise exposure were significantly lower than 3 days after impulse exposure (P<0.05).Expression of Gap-43 in inferior colliculus was significantly up-regulated in the noise exposed groups compared with the normal group (P<0.05 or P<0.01).Expression of Gap-43 was significantly down-regulated 28 days after noise expose compared with 3 days after noise expose(P<0.05).Conclusion Impulse noise exposure leads to significant elevation of ABR thresholds and up-regulation of Gap-43 expression in inferior colliculus.Impulse noise exposure may induce auditory cortex prominent remodeling.