Changes of Auditory Brainstem Response and Expression of Glutamate Decarboxylase -67 in the Auditory Cortex in Rats Following Noise Exposure / 听力学及言语疾病杂志

ABSTRACT

Objective To study changes of auditory brainstem response and expression of glutamate decar-boxylase-67(GAD67) in the auditory cortex in rats following noise exposure .Methods Rats were exposed to a-bove 4 kHz ,100 dB SPL white noise for 2 hours ,then auditory brainstem responses were measurey immediately , and at the 7th and 14th day post-exposure ,and marked GAD67-positive neurons in auditory cortex with immuno-histochemical techniques ,compared with the expression of GAD67 of exposed group to the control .Results ①The auditory threshold for clicks in all rats exposed to noise showed an initial threshold shift ,returned to near control levels at the day 14 .②GAD67-positive neurons 2~4 hours post-exposure increased by 105% than those of in the control group (P<0 .01) ,Then ,at the 7th and 14th day in exposed group were significantly lower than those of in the control group (P<0 .05) .Conclusion These studies describe a temporary threshold shift and increase markers for GAD67 immediately following acoustic exposure ,followed by a decline to below control levels .It may be closely related to noise deafness and other series of auditory dysfunction .