Bilateral Carotid Artery Occlusion Induces Cochlear Oxidative Stress and Hearing Loss in Rat

Introduction: The aim of this study was evaluation the effects of bilateral carotid artery occlusion on cochlear oxidative stress and hearing status in rat. Methods: The rats were divided into two sets. First set used for electrophysiological recording (click and 4 kHz tone burst ABR and EcochG) at day before surgery and 1st, 4th and 7th days after surgery. Animals of second set that used for biochemical analysis. Cochleae of animals in second set were collected at 1st, 4th and 7th days after carotids occlusions for biochemical analysis. For control groups no carotids occlusion took place. To ischemia induction both common carotid arteries were occluded for 20 minutes. Results: Electrophysiological analysis showed ABR thresholds significantly elevated after common carotid arteries occlusion at 1st, 4th and 7th days after surgery and abnormal EcochG results at 75%, 70% and 85% in 1st, 4th and 7th days after surgery respectively. Electrophysiological finding confirmed by biochemical results that showed Malondialdehyde and Nitric oxide levels were increased and Superoxide dismutase and Catalase activities decreased after occlusion in cochleae tissue. Conclusion: this study showed that bilateral common carotid artery occlusion increases cochlear oxidative stress and induces hearing loss in rat.