title: [The changes of carbonic anhydrase activity and its mRNA expression in rats cochlea after noise exposure].
abstract: OBJECTIVE
  To investigate the changes of carbonic anhydrase (CA) activity and its mRNA expression in rats cochlea after noise exposure.
  
  
  METHODS
  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.
  
  
  RESULTS
  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.
  
  
  CONCLUSIONS
  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.
authors.forename: Yanni
authors.initials: Y
authors.lastname: Li
authors.forename: Jianhua
authors.initials: J
authors.lastname: Zhou
mesh_terms: D000818:Animals; D024402:Carbonic Anhydrase II / Q000235:genetics / Q000378:metabolism*; D003051:Cochlea / Q000201:enzymology*; D005260:Female; D008297:Male; D009622:Noise / Q000009:adverse effects*; D012333:RNA, Messenger / Q000235:genetics; D051381:Rats; D017207:Rats, Sprague-Dawley
chemical_list: D012333:RNA, Messenger; D024402:Carbonic Anhydrase II