The protective effect of quercetin against aminoglycoside-induced hair cell loss. (A) Neomycin causes severe hair cell damage. (B) Quercetin (100 μM) protects hair cells against aminoglycoside ototoxicity. Quercetin significantly protects hair cells at concentrations of 10 (p < 0.05), and 100 μM (p < 0.01) in the zebrafish lateral line. *p < 0.05; **p < 0.01.

The quenching effect on the generation of the hydroxyl radical. Hair cells in the neomycin group showed increased signals for H₂DCFDA (D–H) compared with those in the control group (A–C) in 3 min. Staining decreased for four to 5 min (E, F). The signals are reduced in quercetin group (I–M).

Uptake study of Texas-red conjugated gentamicin. Images of a zebrafish neuromast labeled with YOPRO-1 after a 3 min exposure to GTTR. Red fluorescence is GTTR, green is YO-PRO1 labeled hair cell nuclei. In the control group (A), GTTR was uptake in hair cells. GTTR labeling was not affected in administration of quercetin (B). (For interpretation of the references to colour in this figure legend, the reader is referred to the web version of this article.)

The protective effect of quercetin against noise-induced hair cell loss. There were more surviving hair cells in the quercetin group (B) than in the vehicle control group (A) after intense noise exposure. The survival rates of outer hair cells were significantly higher in the quercetin group than in the control group in the cochlear second turn (C). **p < 0.01.