Streptomycin-induced apoptosis of rat cochlear hair cell cultured in vitro
He, J.-c.; Yu, D.-z.; Ding, D.-l.; Yin, S.-k.; Salvi, R.J.
Zhonghua Er Bi Yan Hou Tou Jing Wai Ke Za Zhi 44(6): 494-498
2009
ISSN/ISBN: 1673-0860 PMID: 19954022 Document Number: 629066
To evaluate if caspase pathway was involved in streptomycin-induced cell apoptosis in cochlear hair cells. 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. 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. 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.