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BioMed Research International
Volume 2013 (2013), Article ID 628064, 16 pages
http://dx.doi.org/10.1155/2013/628064
Research Article

Ouabain-Induced Apoptosis in Cochlear Hair Cells and Spiral Ganglion Neurons In Vitro

1Department of Otorhinolaryngology, The First Affiliated Hospital, College of Medicine, Zhejiang University, Hangzhou, Zhejiang 310003, China
2Center for Hearing and Deafness, University at Buffalo, Buffalo, NY 14214, USA

Received 4 July 2013; Accepted 16 August 2013

Academic Editor: Antoni Camins

Copyright © 2013 Yong Fu et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Abstract

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.