Role of Free Radical Formation in Murine Cytomegalovirus–Induced Hearing Loss

Abstract

Objectives: The goal of the study was to determine whether reactive oxygen species (ROS) mediates cytomegalovirus (CMV)–induced labyrinthitis. Study Design: Murine model of CMV infection. Setting: University of Utah laboratory. Subjects and Methods: Nrf2 knockout mice were inoculated with murine CMV. Auditory brainstem response (ABR) and distortion product otoacoustic emissions (DPOAEs) were then performed on these and uninfected controls. BALB/c mice were inoculated with murine CMV to determine whether a marker for ROS production, dihydroethidium (DHE), is expressed 7 days after inoculation. Finally, 2 antioxidants—D-methionine and ACE-Mg (vitamins A, C, and E with magnesium)—were administered 1 hour before and after infection in inoculated mice for 14 days. Temporal bones were harvested at postnatal day 10 for DHE detection. ABR and DPOAE testing was done at postnatal day 30. Scanning electron microscopy was also performed at postnatal day 30 to evaluate outer hair cell integrity. Results: Nrf2-infected mice had worse hearing than uninfected mice (P