Zebrafish larvae are useful for identifying chemicals against lateral line (LL) hair cell (HC) damage and this type of chemical screen mainly focuses on searching for protectors against cell death. To expand the candidate pool of HC protectors, a self-built acoustic escape response (AER)-detecting system was developed to apply both low-frequency near-field sound transmission and AER image acquisition/processing modules. The device quickly confirmed the changed LL HC functions caused by most known ototoxins, protectors, and neural transmission modifiers, or knockdown of LL HC-expressing genes. With ten devices wired in tandem, five 'hit' chemicals were identified from 124 cyclin-dependent kinase inhibitors to partially restore cisplatin-damaged AER in less than a day. AS2863619, ribociclib, and SU9516 among the hits, protected the HCs in the mouse cochlea. Therefore, using free-swimming larval zebrafish, the self-made AER-detecting device can efficiently identify compounds that are protective against HC damage, including cell death and loss-of-function.
Animals ; Zebrafish ; Hair Cells, Auditory/physiology* ; Lateral Line System/cytology* ; Escape Reaction/physiology* ; Larva ; Mice ; Cisplatin/toxicity* ; Drug Evaluation, Preclinical/methods*

Histone deacetylases are involved in many biological processes and have roles in regulating cell behaviors such as cell cycle entry, cell proliferation and apoptosis. However, the effect of histone deacetylases on the development of hair cells (HCs) has not been fully elucidated. In this study, we examined the influence of histone deacetylases on the early development of neuromasts in the lateral line of zebrafish. Hair cell development was evaluated by fluorescent immunostaining in the absence or presence of histone deacetylase inhibitors. Our results suggested that pharmacological inhibition of histone deacetylases with inhibitors, including trichostatin A, valproic acid and MS-275, reduced the numbers of both HCs and supporting cells in neuromasts. We also found that the treatment of zebrafish larvae with inhibitors caused accumulation of histone acetylation and suppressed proliferation of neuromast cells. Real-time PCR results showed that the expression of both p21 and p27 mRNA was increased following trichostatin A treatment and the increase in p53 mRNA was modest under the same conditions. However, the expression of p53 mRNA was significantly increased by treatment with a high concentration of trichostatin A. A high concentration of trichostatin A also led to increased cell death in neuromasts as detected in a TUNEL assay. Moreover, the nuclei of most of these pyknotic cells were immunohistochemically positive for cleaved caspase-3. These results suggest that histone deacetylase activity is involved in lateral line development in the zebrafish and might have a role in neuromast formation by altering cell proliferation through the expression of cell cycle regulatory proteins.
Animals ; Apoptosis ; Cell Proliferation ; Cyclin-Dependent Kinase Inhibitor Proteins/genetics/metabolism ; Histone Deacetylase Inhibitors/*pharmacology ; Histone Deacetylases/*metabolism ; Histones/metabolism ; Larva/growth & development/metabolism ; Lateral Line System/cytology/*growth & development/metabolism ; Mechanoreceptors/drug effects/*metabolism/physiology ; RNA, Messenger/genetics/metabolism ; Zebrafish ; Zebrafish Proteins/*metabolism

Aminoglycoside antibiotics, due to their strong antibacterial effects and broad antimicrobial spectra, have been very commonly used in clinical practice in the past half century. However, aminoglycoside antibiotics manifest severe ototoxicity and nephrotoxicity, and are one of top factors in hearing loss. In this study, three members of the aminoglycoside antibiotics family, gentamycin, neomycin and streptomycin, were chosen as the representatives to be investigated for their toxicity to the embryonic development and the larva hair cells in zebrafish, and also to their target genes associated with hearing-related genes. The results showed that: (1) the lethal effect of all three drugs demonstrated a significant dependence on concentration, and the severity order of the lethal effect was streptomycin > neomycin > gentamycin; (2) all the three drugs caused the larva trunk bending in resting state at 5 dpf (day past fertilization), probably due to their ototoxicity in the physical imbalance and postural abnormalities; (3) impairment and reducing of the hair cells were observed in all three cases of drug treatment; (4) four genes, eya1, val, otx2 and dlx6a, which play an important role in the development of hearing organs, showed differential and significant decrease of gene expression in a drug concentration-dependent manner. This study for the first time reports the relevance between the expression of hearing genes and the three ototoxic antibiotics and also proved the feasibility of establishing a simple, accurate, intuitive and fast model with zebrafish for the detection of drug ototoxicity.
Aminoglycosides ; toxicity ; Animals ; Anti-Bacterial Agents ; toxicity ; Embryonic Development ; drug effects ; Gene Expression Regulation ; Gentamicins ; toxicity ; Hair Cells, Auditory ; cytology ; drug effects ; Hearing Disorders ; chemically induced ; genetics ; metabolism ; Homeodomain Proteins ; metabolism ; Intracellular Signaling Peptides and Proteins ; metabolism ; Larva ; drug effects ; Lateral Line System ; drug effects ; MafB Transcription Factor ; metabolism ; Models, Animal ; Neomycin ; toxicity ; Nerve Tissue Proteins ; metabolism ; Nuclear Proteins ; metabolism ; Otx Transcription Factors ; metabolism ; Protein Synthesis Inhibitors ; toxicity ; Protein Tyrosine Phosphatases ; metabolism ; Streptomycin ; toxicity ; Zebrafish ; embryology ; Zebrafish Proteins ; metabolism