RESUMO
<p><b>OBJECTIVE</b>To evaluate if caspase pathway was involved in streptomycin-induced cell apoptosis in cochlear hair cells.</p><p><b>METHODS</b>F344 rats at postnatal day 3 or 4 were used for the study in cochlear organotypic cultures. The cochlear basilar membrane was micro-dissected out and cultured overnight, and then treated with 1 mmol/L streptomycin for 24 hours. Before the termination, the activity of caspase-8, 9 or 6 were detected with FAM-peptide-FMK labeled caspase-8, 9 or 6, respectively. The stereocilia and cuticular plate of hair cells were stained with TRITC conjugated phalloidin, and the nuclei were stained with Topro-3 DNA probe. The specimens were observed and photographed under confocal fluorescent microscope.</p><p><b>RESULTS</b>Streptomycin with 1 mmol/L causes about 80% cochlear hair cells missing in the basal turn and 10% hair cell loss in the apex. After streptomycin treatment, the nuclear shrinkage and fragmentation were found in most cochlear hair cells, and the caspase-8, caspase-9 and caspase-6 were greatly activated.</p><p><b>CONCLUSIONS</b>Apoptosis is involved in the cochlear hair cells death induced by Streptomycin in vitro. The caspase activities in upstream and downstream are maybe the major apoptotic pathway.</p>