Mitigation of Hearing Damage After Repeated Blast Exposures in Animal Model of Chinchilla.

Abstract

High-intensity sound or blast-induced hearing impairment is a common injury for Service members. Epidemiology studies revealed that the blast-induced hearing loss is associated with the traumatic brain injury (TBI), but the mechanisms of the formation and prevention of auditory injuries require further investigation. Liraglutide, a glucagon-like peptide-1 receptor (GLP-1R) agonist, has been reported as a potential treatment strategy for TBI-caused memory deficits; however, there is no study on therapeutics of GLP-1R for blast-induced hearing damage. This paper reports our current study on progressive hearing damage after repeated exposures to low-level blasts in the animal model of chinchilla and the mitigation of hearing damage using liraglutide. Chinchillas were divided into three groups (N = 7 each): blast control, pre-blast treatment, and post-blast treatment. All animals were exposed to six consecutive blasts at the level of 3-5 psi (21-35kPa) on Day 1. The auditory brainstem response (ABR) was measured on Day 1 (pre- and post-blast) and Days 4, 7, and 14 after blast exposure. Upon the completion of the experiment on Day 14, the brain tissues of animals were harvested for immunofluorescence studies. Significant damage was revealed in blast-exposed chinchillas by increased ABR thresholds, decreased ABR wave I amplitudes, and cell apoptosis in the inferior colliculus in the blast control chinchillas. Treatment with liraglutide appeared to reduce the severity of blast-induced hearing injuries as observed from the drug-treated chinchillas comparing to the blast controls. This study bridges the gap between TBI and hearing impairment and suggests a possible intervention for blast-induced hearing loss for Service members.