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

다국어 초록 (Multilingual Abstract)

Objectives. Aminoglycosides 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.
Methods. The 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.
Results. The 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.
Conclusion. Our 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.

다국어 초록 (Multilingual Abstract)

Objectives. Aminoglycosides 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.
Methods. The 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.
Results. The 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.
Conclusion. Our 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.

참고문헌 (Reference)

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