Drug screening for hearing loss: using the zebrafish lateral line to screen for drugs that prevent and cause hearing loss

Abstract

Several animal models have been used for the study of mechanosensory hair cells and hearing loss. Because of the difficulty of tissue acquisition and large animal size, these traditional models are impractical for high-throughput screening. The zebrafish has emerged as a powerful animal model for screening drugs that cause and prevent hair cell death. The unique characteristics of the zebrafish enable rapid in vivo imaging of hair cells and hair cell death. We have used this model to screen for and identify multiple drugs that protect hair cells from aminoglycoside-induced death. The identification of multiple drugs and drug-like compounds that inhibit multiple hair cell death pathways might enable the development of protective cocktails to achieve complete hair cell protection.

Figure 1

[E15] (a) Live preparation of fluorescently labeled zebrafish larva five days post-fertilization. Neuromasts of the lateral line are stained with YO-PRO-1. Scale bar = 0.5 mm. (b) Schematic illustration of a neuromast. Hair cells are depicted in green with long kinocilia and shorter stereocilia projecting from the apical end of the cells and afferent and efferent nerve fibers at the basal end. Support cells (orange cells) intercalate between the hair cells. Reproduced, with permission from the Association for Research in Otolaryngology, from Ref. [31][E16].

Figure 2

Examples of normal and damaged fluorescently labeled hair cells of the zebrafish lateral line. YO-PRO1 selectively labels hair cell nuclei in (a) normal and (b) neomycin-damaged neuromasts. Hair cell protection can thus be assessed easily during screening. For quantitative hair cell counts, FM1-43FX is used to count (c) normal and (d) neomycin-damaged hair cells. In the undamaged neuromast (c), there are approximately 12 visible hair cells. In the damaged neuromast (d), there are two surviving hair cells (arrows) after treatment with one hour of neomycin. Scale bar in (d) = 10 μM and applies to all panels. Reproduced, with permission from the Association for Research in Otolaryngology, from Ref. [40].[E17]