Effect of low level laser on ototoxicity prevention of FM1-43 in postnatal organotypic culture of rat utricles

Abstract

Backgrounds and Objectives: The styryl pyridinium dye FM1-43 is nontoxic, fluorescent, cationic dye whose fluorescence markedly increases after partitioning into membrane. Rapid entry of FM1-43 is inhibited by drugs that block the mechanically gated transduction channels, suggesting the dye can itself act as a permanent blocker of the channels. In this study, the effects of low level laser (LLL) and FM1-43 on gentiamicin induced ototoxicity in postnatal organotypic culture of rat utricles were investigated. Materials and Methods: An organotypic culture of 2- 7-day-old rat utricular maculae was established. In a series of experiments utricles were exposed to either irradiation of low level laser(LG group)or 10 ?M FM1-43(FG group) or both(LFG group) followed by 1mM of gentamicin treatment for 12 hrs. The results of experimental groups were compared with the control group by confocal laser scanning and scanning electron microscopy. Results: LLL prevented vestibular hair cells ototoxicity. Rapid incubation with FM1-43 dye protected vestibular hair cell damage induced by gentamicin treatment. Substantial additive effect of LLL on ototoxicity prevention was noted in combination therapy with FM1-43. There were statistical significant differences among all groups but between control and LFG group by both confocal laser scanning and scanning electron microscopy. In addition, caspase-3 activity was hardly found in LFG group after double staining with Phalloidin-FITC by confocal laser scanning microscopy. Conclusion: These results suggest that there is an additive protection effect of LLL and FM1-43 against gentamicin ototoxicity in postnatal organotypic culture of rat utricles. LLL may have clinical preventive and therapeutic implications on ototoxicity.