The changes of carbonic anhydrase activity and its mRNA expression in rats cochlea after noise exposure / 临床耳鼻咽喉头颈外科杂志

ABSTRACT

OBJECTIVE@#To investigate the changes of carbonic anhydrase (CA) activity and its mRNA expression in rats cochlea after noise exposure.@*METHOD@#Twenty-four healthy Sprague Dawley rats were randomly allocated into 4 groups including 1 control group without contact of noise and 3 experimental groups exposed to a narrowband white noise of 4 kHz, 110 dB SPL 4h/d for 1 day, 1 week and 3 weeks, respectively. ABR thresholds were tested for each group at the time points described above. An immunohistochemical method was used to detect the expression of CA in the cochlea tissue. Differences in CAII mRNA expressions with and without noise exposure were examined using RT-PCR.@*RESULT@#The thresholds of ABR in noise exposed cochlea were increased compared with the control cochlea (P < 0.01). CA activity and the CAII mRNA expression in noise exposed cochlea were decreased compared with the control cochlea (P < 0.01). The increase of ABR thresholds and decreases of CA activity and the CAII mRNA expression showed a time dependent pattern as the extension of duration exposed to noise.@*CONCLUSION@#Noise exposure could downregulate the CA activity and CAII mRNA expression in the cochlea. CA was proably involved in the pathogenesis of noise-induced hearing loss.