Sodium Selenite Acts as an Otoprotectant against Neomycin-Induced Hair Cell Damage in a Zebrafish Model

Abstract

Sodium selenite is a trace element essential for many physiological functions in the body. It is involved in various biological processes; it acts as a cofactor for antioxidant enzymes that protect against free radicals and is reported to limit metal-mediated oxidative DNA damage. In the present study, we investigated the effect of sodium selenite on neomycin ototoxicity in wild-type and transgenic zebrafish (Brn3C: EGFP). Five or six days post-fertilization, zebrafish larvae were co-exposed to 125 μM neomycin and various concentrations (10 μM, 100 μM, 250 μM, and 500 μM) of sodium selenite for 1 h. Hair cells within neuromasts of the supraorbital (SO1 and SO2), otic (O1), and occipital (OC1) lateral lines were analyzed by fluorescence microscopy (n = 10 fish per treatment). Hair cell survival was estimated as the ratio of the hair cell numbers in each group compared to those of the control group that were not exposed to neomycin. Apoptosis and hair cell damage of neuromasts were evaluated using the terminal deoxynucleotidyl transferase (TdT)-mediated dUTP-biotin nick end labeling (TUNEL) assay and 2-[4-(dimethylamino) styryl]-N-ethylpyridinium iodide (DASPEI) assay, respectively. Ultrastructural changes were evaluated using scanning electron microscopy and transmission electron microscopy. Neuromast hair cells were preserved in zebrafish exposed to 125 μM neomycin and 500 μM sodium selenite for 1 h. Sodium selenite protected against neomycin-induced hair cell loss of neuromasts, reduced apoptosis, and prevented zebrafish ultrastructural changes. We propose that sodium selenite protects against neomycin-induced hair cell damage by inhibiting apoptosis, decreasing the disarray of stereocilia, and preventing ultrastructural changes in the neuromast hair cells of the zebrafish.

A new aminoglycoside etimicin shows low nephrotoxicity and ototoxicity in zebrafish embryos

“…Previous studies proposed that AG‐induced hair cell death is mediated by ROS, and the ROS subsequently cause either direct or indirect hair cell damage (Chang et al, 2016). The antioxidants or ROS scavengers have otoprotective activities in AG‐treated hair cells (Owens et al, 2008; Park et al, 2017).…”

Impact of Nicotine Exposure on Hair Cell Toxicity and Embryotoxicity During Zebrafish Development

“…Tg (brn3c:EGFP) and Tg (cmlc2:EGFP) express green fluorescence characteristically in hair cells and myocardial cells, allowing evaluation of heart size, respectively. The wild type and Tg zebrafish larvae were produced by paired matings of age-matched adult fish, and larvae were sustained at a density of approximately 50 embryos per 100-mm petri dish in embryo media as previously described [ 20 ].…”

“…The DASPEI-stained area within SO1, SO2, O1, and OC1 was examined under a fluorescence microscope and measured using Image J (ver. 1.48; National Institutes of Health, Bethesda, MA, USA) as we previously described [ 20 ]. The average area of DASPEI staining in neuromasts was compared among all experimental groups and the control group (n=6 fish for each group).…”

“…The 5-dpf wild-type larvae exposed to 5 μM and 40 μM nicotine and normal controls were prefixed by immersion in 2% glutaraldehyde in 0.1 M phosphate buffer and postfixed for 2 hours in 1% osmic acid dissolved in phosphate-buffered saline. Larvae were managed in a graded series of ethanol and t-butyl alcohol, dehydrated in a freeze dryer (ES-2030; Hitachi, Tokyo, Japan), platinum coated using an ion coater (IB-5; Eiko, Tokyo, Japan) and investigated using scanning electron microscopy (SEM; S-4700; 2,500, 3,000, 5,000× magnification, Hitachi) as previously described [ 20 ].…”

Evaluation of Ototoxicity of an Antifog Agent and the Suspected Underlying Mechanisms: An Animal Study

“…The larvae were washed thrice with embryo medium after treatment and anesthetized using tricaine (3-aminobenzoic acid ethyl ester, 0.4 g/100 mL; pH adjusted to 7.0 using Tris buffer) for 5 minutes as described in previous studies. 16,17 They were then mounted on a depression slide using methylcellulose and observed under a fluorescence microscope (LSM5 PASCAL, Carl Zeiss, Germany) at 40Â magnification.…”