stilbenes and Hearing-Loss--Noise-Induced

Modern-day high performance aircraft are more powerful, more efficient, and, unfortunately, frequently produce high noise levels, resulting in noise-induced hearing loss (NIHL) in military aircrew. Military pilots are required to perform many flight duties correctly in the midst of many challenges that may affect mission completion as well as aircraft and aircrew safety. NIHL can interfere with successful mission completion. NIHL may also require aircrew to be downgraded from flying duties, with the incumbent re-training costs for downgraded personnel and training costs for new/replacement aircrew. As it is not possible to control the source of the noise without compromising the efficiency of the engine and aircraft, protecting the aircrew from hazards of excessive noise and treating NIHL are of extreme importance. In this article we discuss various personal hearing protection devices and their efficacy, and pharmacological agents for prevention and management of NIHL.

Topics: Acetylcarnitine; Acetylcysteine; Aerospace Medicine; Aircraft; Anti-Inflammatory Agents; Antioxidants; Azoles; Creatine; Ear Protective Devices; Equipment Design; Excitatory Amino Acid Antagonists; Free Radical Scavengers; Genetic Therapy; Hair Cells, Auditory; Head Protective Devices; Hearing Loss, Noise-Induced; Humans; Hyperbaric Oxygenation; Isoindoles; Magnesium; Methionine; Military Personnel; Nanomedicine; Neuroprotective Agents; Organoselenium Compounds; Regeneration; Resveratrol; Salicylic Acid; Stilbenes; Vitamins

To investigate the potential preventive effect of resveratrol in rats exposed to acoustic trauma (AT).. In this experimental study, Wistar albino rats were divided into three groups: Group 1 (Control, n = 6), Group 2 (AT, n = 6), and Group 3 (resveratrol + AT). The rats in Group 2 were exposed to AT. The rats in Group 3 received resveratrol (300 mg/kg/day) via gavage for 7 days. On day 7, the rats were exposed to AT 10 min following resveratrol treatment. Histological sections of the cochleae were examined using light microscopy, transmission (TEM), and scanning electron microscopy (SEM).. The cochlear hair cells, stereocilia, and Deiters' cells of the control group appeared normal in all microscopic evaluations. In Group 2, light microscopy revealed predominantly inner hair cell loss, although the outer hair cells were affected. TEM and SEM examination showed severe loss of stereocilia and SEM revealed stereocilia arranged in an asymmetric array. The cochlear structure in Group 3 appeared well preserved under the light microscope, and although TEM and SEM revealed stereocilia loss, the hair cells and stereocilia appeared near normal compared with those of Group 2.. Resveratrol may have a protective effect against AT damage in the cochlea, most likely through its antioxidant activity. Our results may be useful for studies in humans exposed to AT and noise-induced hearing loss related to chronic exposure to occupational noise.

Topics: Animals; Cochlea; Hair Cells, Auditory; Hearing Loss, Noise-Induced; Microscopy, Electron, Scanning; Rats; Rats, Wistar; Resveratrol; Stilbenes

Our previous studies have demonstrated the efficacy of resveratrol, a grape constituent noted for its antioxidant and anti-inflammatory properties, in reducing temporary threshold shifts and decreasing cochlear hair cell damage following noise exposure. This study was designed to identify the potential protective mechanism of resveratrol by measuring its effect on cyclooxygenase-2 (COX-2) protein expression and reactive oxygen species (ROS) formation following noise exposure.. Controlled animal intervention study.. Otology Laboratory, Henry Ford Health System.. Twenty-two healthy male Fischer 344 rats (2-3 months old) were exposed to acoustic trauma of variable duration with or without intervention. An additional 20 healthy male rats were used to study COX-2 expression at different time points during and following treatment of 24 hours of noise exposure. Cochlear harvest was performed at various time intervals for measurement of COX-2 protein expression via Western blot analysis and immunostaining. Peripheral blood was also obtained for ROS analysis using flow cytometry.. Acoustic trauma exposure resulted in a progressive up-regulation of COX-2 protein expression, commencing at 8 hours and peaking at 32 hours. Similarly, ROS production increased after noise exposure. However, treatment with resveratrol reduced noise-induced COX-2 expression as well as ROS formation in the blood as compared with the controls.. COX-2 levels are induced dramatically following noise exposure. This increased expression may be a potential mechanism of noise-induced hearing loss (NIHL) and a possible mechanism of resveratrol's ability to mitigate NIHL by its ability to reduce COX-2 expression.

Topics: Animals; Antioxidants; Cochlea; Cyclooxygenase 2; Hearing Loss, Noise-Induced; Male; Rats; Rats, Inbred F344; Resveratrol; Stilbenes

The purpose of the study is to test the ability of resveratrol to protect the auditory system from reactive oxygen species (ROS)-mediated noise damage. Oxidative stress is mediated by ROS, which are known to cause cellular and molecular damage. Interfering with this process, using ROS inhibitors/scavengers such as antioxidants has shown promise in protecting specific systems from oxidative damage. Among the antioxidants receiving recent attention is resveratrol, an active component in red wine. Study design and setting Ten Fischer rats were used for this study. The experimental group (n = 5) received 7 weeks of resveratrol treatment (430/microg/kg/day), by gavage, and the control group (n = 5) received normal saline solution by gavage. Baseline auditory brainstem responses (3, 6, 9, 12 and 18 kHz) were determined for both groups. After 21 days, animals were exposed to noise (105 dB, 4500 to 9000 Hz for 24 hours). Postnoise auditory brainstem responses were assessed at 4 recovery time points: immediate, at 3 days, 7 days, and 4 weeks after noise exposure.. Results demonstrate that the resveratrol group showed reduced threshold shifts compared with the control group after noise exposure. These shifts were significantly different between groups at 6 and 9 kHz (P < 0.05), corresponding to the region most represented by the frequency of the traumatic noise.Conclusion/significance Initial studies in our laboratory as well as other investigators have shown the importance of specific antioxidant therapy in the prevention of ischemic, noise, and age related hearing loss. The current study demonstrates a protective effect of resveratrol on noise-induced hearing loss.

Topics: Animals; Antioxidants; Auditory Threshold; Cochlea; Evoked Potentials, Auditory, Brain Stem; Hearing Loss, Noise-Induced; Male; Oxidative Stress; Random Allocation; Rats; Rats, Inbred F344; Reactive Oxygen Species; Resveratrol; Stilbenes