Changes in Calcium/Calmodulin Level and Mitochondrial Membrane Potential in Cochlear Neurons of Newborn Mice Infected with Murine Cytomegalovirus

Abstract

We sought to elucidate the pathogenesis of hearing loss in newborns due to congenital cytomegalovirus. We used the model of murine cytomegalovirus (MCMV) infection and evaluated concentrations of free calcium, calmodulin levels, and mitochondrial membrane potential in cochlear neurons of infected newborn mice. MCMV infection was established by intracranial inoculation of newborn mice with viral suspension (20 μl of MCMV TCID(50)--10(4) IU/0.1 ml); the mice in control group were injected 0.9 % NaCl. Concentration of intracellular free calcium concentration ([Ca(2+)] i ), mitochondrial membrane potential, and the mRNA level of calmodulin (CaM) in the cochlear neurons were evaluated, when the mice were 1 month old. Compared with control group, intracellular [Ca(2+)] i and CaM mRNA levels significantly (p < 0.05; both comparisons) increased, while the mitochondrial membrane potential significantly (p < 0.05) decreased in the MCMV-infected group. In conclusion, alteration of [Ca(2+)] i and CaM levels and mitochondrial membrane potentials in cochlear neurons may be the pathological basis of sensorineural hearing loss associated with MCMV infection.