Effects of Exposure to Cigarette Smoke on Distortion-Product Otoacoustic Emissions in Rats

Abstract

Background: Different types of direct and passive smoking have been reported to be associated with conductive and sensorineural hearing loss. In this study, we aimed to investigate the relationship between cigarette smoke exposure and cochlear dysfunction. Methods: In this experimental study, 12 male Wistar rats were divided into 2 groups: control group without exposure and smoke-exposed group housed in a whole-body exposure chamber (exposed to the smoke of 20 cigarettes; 9 ± 1 mg of tar and 0.8 ± 0.1 mg of nicotine per cigarette) for 8 hours a day during 10 consecutive days. The main and side stream smoke was generated in accordance with the federal trade commission (FTC) regimen (2-second puff with 35 mL volume and frequency of 1 puff per minute). Distortion-product otoacoustic emissions (DPOAEs) were evaluated at a frequency range of 4620 - 9960 Hz at baseline and 1, 7, and 21 days after exposure. Repeated measures ANOVA and t test were performed for data analysis, using SPSS version 18. Results: In the smoke-exposed animals, temporary hearing changes were significantly different from the baseline at a greater attenuation and higher frequencies (P 0.05). Conclusions: Subacute smoke exposure for 10 days resulted in the temporary reduction of DPOAEs. Chronic and subchronic effects of smoke on permanent hearing damage need to be investigated through further animal studies.