01 August 2008
Med Sci Monit 2008; 14(8): BR159-164 :: ID: 869487
The cellular mechanisms leading to noise-induced hearing loss (NIHL) involve the generation of reactive oxygen species (ROS). Recent studies on glutathione (GSH) and N-acetylcysteine (NAC) show that they can protect the cochlea from ROS-derived damage, increasing the levels of endogenous cellular defences. The purpose of this study was to verify NAC's oto-protective efficacy and determine if drug administration timing influences the degree of oto-protection.
Material and Method
Forty male Sprague Dawley albino rats were divided in four groups exposed to 8-kHz 105-dB SPL continuous noise. The groups were treated with diverse NAC administration modalities: group A received 4 injections during 48 hours (pre- and post-noise exposure), group B 1 injection prior to exposure, group C 1 injection 24 h after exposure, and group D served as untreated controls. The single injection dosage was 375 mg/kg; the controls received an equal volume of saline solution. Cochlear function was assessed by pre- and post-noise (after 168 hours) recordings of distortion product otoacoustic emissions (DPOAEs) and auditory brainstem responses (ABR). DPOAEs were obtained by three different asymmetric protocols (P1=60-50, P2=50-40, P3=40-30 dB SPL) for frequencies of 4-16 kHz. ABR responses were elicited by tone-bursts at 8 and 16 kHz.
The most important outcome of the study was that the administration of NAC significantly reduced the threshold shifts in the treated animals. NAC provided different degrees of threshold reduction according to the timing of the drug injection.
The role played by the timing of NAC injection was important for the OHC protection index. From a DPOAE perspective, the best protection scheme was observed in the group receiving NAC after noise exposure, but full recovery of cochlear function was not observed in any of the tested groups.
Keywords: Rats, Otoacoustic Emissions, Spontaneous - drug effects, Rats, Sprague-Dawley, Evoked Potentials, Auditory, Brain Stem - drug effects, Hearing Loss, Noise-Induced - physiopathology, Auditory Threshold - drug effects, Acetylcysteine - therapeutic use
01 December 2021 : EditorialEditorial: Cardiovascular Complications at One Year After SARS-CoV-2 Infection are Independent of Underlying Cardiovascular Risk Factors or Severity of COVID-19
Med Sci Monit 2022; 28:e937048
04 May 2022 : Clinical ResearchEffects of Wearing Face Masks on Exercise Capacity and Ventilatory Anaerobic Threshold in Healthy Subjects ...
Med Sci Monit In Press; DOI: 10.12659/MSM.936069
22 April 2022 : Clinical ResearchFactors Associated with Falls During Hospitalization for Coronavirus Disease 2019 (COVID-19)
Med Sci Monit In Press; DOI: 10.12659/MSM.936547
27 April 2022 : Meta-AnalysisEffect of the COVID-19 Pandemic on Serum Vitamin D Levels in People Under Age 18 Years: A Systematic Review...
Med Sci Monit In Press; DOI: 10.12659/MSM.935823
20 May 2022 : Clinical ResearchEfficacy of Focused Extracorporeal Shock Wave Therapy in Chronic Low Back Pain: A Prospective Randomized 3-...
Med Sci Monit In Press; DOI: 10.12659/MSM.936614
19 May 2022 : Clinical ResearchAssociation Between Serum Homocysteine Levels and Severity of Diabetic Kidney Disease in 489 Patients with ...
Med Sci Monit In Press; DOI: 10.12659/MSM.936323
18 May 2022 : Clinical ResearchPhysical and Psychosocial Concept Domains Related to Health-Related Quality of Life (HRQL) in 50 Girls and ...
Med Sci Monit In Press; DOI: 10.12659/MSM.936801
Most Viewed Current Articles
31 Dec 1969 : Clinical ResearchRetrospective Study of Outcomes and Hospitalization Rates of Patients in Italy with a Confirmed Diagnosis o...
Med Sci Monit 2021; 27:e935379
31 Dec 1969 : Review articleA Review of the Potential Roles of Antioxidant and Anti-Inflammatory Pharmacological Approaches for the Man...
Med Sci Monit 2022; 28:e936292
31 Dec 1969 : Review articleLong-Term Respiratory and Neurological Sequelae of COVID-19
Med Sci Monit 2020; 26:e928996