Observation of permeability of blood-labyrinth barrier during cytomegalovirus-induced hearing loss.

OBJECTIVE:Congenital cytomegalovirus (CMV) infection is the most common infectious cause of sensorineural hearing loss in children. This study aims to investigate the pathogenesis CMV-induced hearing loss from the view of integrity of blood-labyrinth-barrier (BLB). METHODS:Newborn BALB/c mice were randomly divided into three groups (n=22, respectively): CMV group, control group and normal group. The CMV group and control group were intracerebrally injected with equal volume (15 μl) of murine CMV (MCMV; 10(4)IU/0.1 ml) and PBS, respectively, and normal group did not receive any treatment. After three weeks, auditory-evoked brainstem response was assessed, and permeability of BLB was evaluated by Evans blue method. Means between groups were compared using t-test. RESULTS:We observed that mice injected with MCMV had a hearing loss and it was connected with the permeability changes of BLB. Besides, using hematoxylin-eosin staining, we noticed hyperaemia in stria vascularis and spiral ligament and bleeding in scala vestibule and scala tympani in CMV group. CONCLUSION:All these data indicated the possible association between CMV-induced hearing loss and BLB dysfunction with the characteristics of inflammation. Our data provide a possible path to investigate the mechanism of CMV-induced hearing damage.