Ouabain-induced apoptosis in cochlear hair cells and spiral ganglion neurons in vitro.
Ouabain is a common tool to explore the pathophysiological changes in adult mammalian cochlea in vivo. In prior studies, locally administering ouabain via round window membrane demonstrated that the ototoxic effects of ouabain in vivo varied among mammalian species. Little is known about the ototoxic effects in vitro. Thus, we prepared cochlear organotypic cultures from postnatal day-3 rats and treated these cultures with ouabain at 50, 500, and 1000 μM for different time to elucidate the ototoxic effects of ouabain in vitro and to provide insights that could explain the comparative ototoxic effects of ouabain in vivo. Degeneration of cochlear hair cells and spiral ganglion neurons was evaluated by hair-cell staining and neurofilament labeling, respectively. Annexin V staining was used to detect apoptotic cells. A quantitative RT-PCR apoptosis-focused gene array determined changes in apoptosis-related genes. The results showed that ouabain-induced damage in vitro was dose and time dependent. 500 μM ouabain and 1000 μM ouabain were destructively traumatic to both spiral ganglion neurons and cochlear hair cells in an apoptotic signal-dependent pathway. The major apoptotic pathways in ouabain-induced spiral ganglion neuron apoptosis culminated in the stimulation of the p53 pathway and triggering of apoptosis by a network of proapoptotic signaling pathways.
Department of Otorhinolaryngology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China ; Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA.
Yong
Y
Fu
Dalian
D
Ding
Lei
L
Wei
Haiyan
H
Jiang
Richard
R
Salvi
D000818:Animals; D017209:Apoptosis / Q000187:drug effects*; D002478:Cells, Cultured; D004791:Enzyme Inhibitors / Q000009:adverse effects* / Q000494:pharmacology; D020869:Gene Expression Profiling; D005786:Gene Expression Regulation / Q000187:drug effects; D006198:Hair Cells, Auditory / Q000378:metabolism* / Q000473:pathology; D009474:Neurons / Q000378:metabolism* / Q000473:pathology; D010042:Ouabain / Q000009:adverse effects* / Q000494:pharmacology; D051381:Rats; D017207:Rats, Sprague-Dawley; D020133:Reverse Transcriptase Polymerase Chain Reaction; D015398:Signal Transduction / Q000187:drug effects; D013136:Spiral Ganglion / Q000378:metabolism* / Q000473:pathology
D004791:Enzyme Inhibitors; D010042:Ouabain