Antioxidant and Anti-Apoptotic Effect of Melatonin on the Vestibular Hair Cells of Rat Utricles

• Main Authors: Jeong-Beom Kim, Jae Yun Jung, Jin-Chul Ahn, Chung Ku Rhee, Hee-Jun Hwang
• Format: Article
• Language: English
• Published: Korean Society of Otorhinolaryngology-Head and Neck Surgery 2009-03-01
• Series: Clinical and Experimental Otorhinolaryngology
• Subjects: Melatonin; Ototoxicity; Antioxidants; Utricle
• Online Access: http://www.e-ceo.org/upload/pdf/ceo-2-6.pdf

ObjectivesAminoglycosides are commonly used antibiotic agents, and they are known to generate free oxygen radicals within the inner ear and to cause vestibulo-cochlear toxicity and permanent damage to the sensory hair cells and neurons. Melatonin, a pineal secretory product, has the properties of being a powerful direct and indirect antioxidant. The aim of the present study was to prove the antioxidant effect of melatonin against gentamicin-induced ototoxicty.MethodsThe utricular maculae of Sprague-Dawley rats were prepared from postnatal day 2-4, and these maculae were were divided into 6 groups as follows: 1) control, 2) melatonin only, 3) gentamicin only, and 4), 5), and 6) gentamicin plus melatonin (10, 50, and 100 µM, respectively). To count the number of hair cells, 5 utricles from each group were stained with phalloidin-FITC on the 1st, 4th, and 7th days after drug administration. Reactive oxygen species (ROS) was assessed by using the fluorescent probe hydrofluorescent diacetate acetyl ester. The caspase-3 activity was also examined with using the fluorescent caspase-3 substrate and performing Western blotting.ResultsThe result of this study showed that gentamicin induced the loss of utricular hair cells, and this loss of hair cells was significantly attenuated by co-administration of melatonin. Melatonin reduced ROS production and caspase-3 activation in the gentamicin treated utricular hair cells.ConclusionOur findings conclusively reveal that melatonin has protective effects against gentamicin-induced hair cell loss in the utricles of rat by inhibiting both ROS production and caspase-3 activity.