Effect of moderate intensity noise exposure on the cochlea of adult male guinea pig and the possible protective role of Pravastatin: Histological study

Abstract

Introduction: Noise induced hearing loss, which is the second most common type of sensorineural hearing loss after presbycusis, is an irreversible disorder but potentially preventable. Extensive studies have documented the damaging effects of high intensity acoustic overexposures on the cochlea, but only few works have focused on the danger of overexposure to moderate intensity noise. Statins recently attracted more attention due to their pleotropic effects.Aim: To evaluate the structural changes in the cochlea of adult male guinea pigs exposed to moderate intensity noise and to assess the possible protective role of Pravastatin.Materials and Methods: Twenty four adult male guinea pigs were included. They were divided into three groups. Group I: served as a control group. Group II: animals were exposed to noise 70-90 dB 6 hours/day for 6 wk. Group III: animals were exposed to noise for the same duration and received Pravastatin 20 mg/kg/day once daily from the 1st day of exposure for 6 weeks.Results: Light and scanning electron microscopic examination of the cochleae of group II revealed that noise exposure resulted in extensive degrees of damage to the hair cells, their stereocilia, stria vascularis and spiral ganglia. Administration of Pravastatin resulted in improvement of the cochlear structures compared to the noise exposed group. Morphometric and statistical study confirmed the previous results.Conclusion: Pravastatin daily administration during exposure to moderate intensity noise showed protective effects on the cochlear structure of guinea pig.