Meeting Abstract
Aminoglycoside antibiotics are toxic to hair cells of the mechanosensory lateral line system in fish. These antibiotics damage hair cells located in neuromasts and have varying effects between the two physiologically distinct types of neuromasts. Superficial neuromasts are on the skin surface and detect water velocity, while canal neuromasts are located in canals and detect water acceleration. Selectively inactivating one of the two types of neuromasts can show its role in lateral line-mediated behaviors, such as schooling. Gentamycin is commonly used in conjunction with streptomycin to selectively inactivate canal and superficial neuromasts, respectively. However, recent studies have suggested that gentamycin does not have differential effects between the two neuromast types, and that gentamycin is capable of inactivating both types in 24 hrs. To determine the shortest exposure needed to inactivate lateral line hair cells, we tested the effects of neomycin, streptomycin, and cobalt chloride on the lateral line system of giant danios (Devario aequipinnatus). We exposed giant danios to 400 μM neomycin, 400 μM streptomycin, or 0.1 mM cobalt chloride and immediately quantified hair cell inactivation using a fluorescent vital stain (4-di-2-asp) at different time points. Our findings suggest that neomycin and streptomycin caused a significant reduction in fluorescence in both superficial and canal neuromasts compared to control fish at similar exposure times. Although these chemicals inactivated superficial neuromasts at a faster rate than canal neuromasts, ultimately both neuromasts types were negatively affected by the aminoglycoside ototoxicity. Cobalt chloride also inactivated hair cells in both neuromast types, but in ~4 hrs. Thus, all neuromasts were inactivated by the three chemicals tested here and not selectively.
