Dexmedetomidine Preconditioning Attenuates Cisplatin-Induced Ototoxicity in Zebrafish

OBJECTIVES Utilisation of high-frequency drills is known to increase noise induced hearing loss due to increasing the damages of inner ear cells. This study aimed to investigate whether preconditioning by using dexmedetomidine (DEX) decreased the occurrence of ischemia in inner cells of the ear. METHODS We utilised a transgenic zebrafish line Brn3C, and the embryos were collected from breeding adult zebrafish. Five-day-old larvae were cultured at the density of 50 embryos, and the larvae were classified into 4 groups: control, cisplatin group, DEX group, and DEX+yohimbine; adrenoreceptor blocker group. The DEX group was categorised into 3 subgroups by dosage; 0.1, 1, and 10 µM. Preconditioning was performed for 150 minutes and then exposed to cisplatin for 6 hours. The experiment was performed in 7 replicates for each group and the number of hair cells in 3 parts of the neuromasts of each fish was determined. RESULTS Hair cell apoptosis by cisplatin was attenuated more significantly in the DEX preconditioning group than in the control group. However, the preconditioning effects were not blocked by yohimbine. CONCLUSION The results of this study suggest that hearing loss caused by vibration-induced noise could be reduced by using DEX and may occur through other mechanisms rather than adreno-receptors.