title: [Changes of hearing threshold and calcium/calmodulin in the cochlear nucleus cells of mice with cytomegalovirus intracranial infection].
abstract: OBJECTIVE
  To explore the changes in the threshold of auditory brainstem response (ABR) and [Ca(2+)]I and calmodulin (CaM) in cochlear nucleus of newborn mice infected by murine cytomegalovirus (MCMV) in the brain.
  
  
  METHODS
  Sixty-nine newborn mice were randomized into model group and control group. The model group (54 mice) was established by intracranial injection with MCMV viral suspension 20 l and the same volume of 0.9% sodium chloride was injected in the control group (15 mice). After 1 month, the ABR was tested in a sound-electric screen environment and the threshold was recorded. Then intracellular free calcium [Ca(2+)]i and the mRNA level of CaM in the cochlear nucleus were assayed by flow cytometry and RT-PCR.
  
  
  RESULTS
  Compare to the control group [(64.0 ± 1.3) dBSPL], the threshold of ABR in the model group [(84.5 ± 2.7) dBSPL] was increased (F = 2.789,P = 0.000). Moreover, in the model group the intracellular free calcium [Ca(2+)]i and the mRNA level of CaM in the cochlear nucleus were increased (F = 1.290, P = 0.000; F = 4.252, P = 0.023), and the differences were statistically significant.
  
  
  CONCLUSIONS
  The intracranial injection of MCMV can lead to abnormal changes in the threshold of ABR in mice, and the change of [Ca(2+) ]I/CaM in cochlear nucleus may be the important pathological basis of sensorineural hearing loss induced by MCMV infection.
authors.affiliation: Department of Otorhinolaryngology Head and Neck Surgery, Affiliated Hospital of Xuzhou Medical College, Xuzhou 221006, China.
authors.forename: Cai-ji
authors.initials: CJ
authors.lastname: Wang
authors.forename: Yue-hua
authors.initials: YH
authors.lastname: Qiao
authors.forename: Qin
authors.initials: Q
authors.lastname: Li
authors.forename: Pei-hua
authors.initials: PH
authors.lastname: Li
authors.forename: Hong
authors.initials: H
authors.lastname: Meng
authors.forename: Ling-jian
authors.initials: LJ
authors.lastname: Meng
authors.forename: Xuan-yi
authors.initials: XY
authors.lastname: Li
authors.forename: Xiao-lu
authors.initials: XL
authors.lastname: Pei
mesh_terms: D016475:3T3 Cells; D000818:Animals; D001309:Auditory Threshold; D002118:Calcium / Q000378:metabolism*; D002147:Calmodulin / Q000378:metabolism*; D020805:Central Nervous System Viral Diseases / Q000378:metabolism* / Q000821:virology; D017626:Cochlear Nucleus / Q000378:metabolism*; D003587:Cytomegalovirus; D003586:Cytomegalovirus Infections / Q000378:metabolism*; D016057:Evoked Potentials, Auditory, Brain Stem; D005260:Female; D008297:Male; D051379:Mice; D008807:Mice, Inbred BALB C
chemical_list: D002147:Calmodulin; D002118:Calcium