Channy Park1, Hyewon Lim2, Sung K Moon3, Raekil Park1. 1. 1 Laboratory of Peroxisomes & Lipid Metabolism, Department of Biomedical Science and Engineering, Gwangju Institute of Science and Technology, Gwangju, Republic of Korea. 2. 2 Department of Obstetrics and Gynecology, Iksan Hospital, Jeonbuk, Korea. 3. 3 Department of Head and Neck Surgery, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
Abstract
OBJECTIVES: Auditory neuropathy due to toxicity mechanism of pyridoxine has not yet been fully documented. Therefore, the present study explored a direct mechanism underlying the effects of pyridoxine on auditory neuropathy in organ of Corti (OC) explants ex vivo and cochlear neuroblast cell line, VOT-33 in vitro. METHODS: Primary OC explants containing spiral ganglion neurons and cultured VOT-33 cells were treated with pyridoxine. RESULTS: In nerve fiber of primary OC explants, pyridoxine decreased staining for NF200, a neuro-cytoskeletal protein. We also found that pyridoxine-induced VOT-33 apoptosis, as indicated by accumulation of the sub-G0/G1 fraction, caspase-3 activation, and PARP cleavage. In addition, pyridoxine induced reactive oxygen species (ROS) generation and alteration of mitochondrial membrane potential transition (MPT), including Bcl-2 family protein expression and consequently Ca2+ accumulation and changes of endoplasmic reticulum (ER) stress-related protein expression such as phospho-PERK, caspase-12, Grp78, and CHOP. CONCLUSION: Pyridoxine preferentially induced severe cell death on nerve fiber in primary OC explants and markedly increased apoptotic cell death via mitochondria-mediated ER stress in VOT-33 cells.
OBJECTIVES: Auditory neuropathy due to toxicity mechanism of pyridoxine has not yet been fully documented. Therefore, the present study explored a direct mechanism underlying the effects of pyridoxine on auditory neuropathy in organ of Corti (OC) explants ex vivo and cochlear neuroblast cell line, VOT-33 in vitro. METHODS: Primary OC explants containing spiral ganglion neurons and cultured VOT-33 cells were treated with pyridoxine. RESULTS: In nerve fiber of primary OC explants, pyridoxine decreased staining for NF200, a neuro-cytoskeletal protein. We also found that pyridoxine-induced VOT-33 apoptosis, as indicated by accumulation of the sub-G0/G1 fraction, caspase-3 activation, and PARP cleavage. In addition, pyridoxine induced reactive oxygen species (ROS) generation and alteration of mitochondrial membrane potential transition (MPT), including Bcl-2 family protein expression and consequently Ca2+ accumulation and changes of endoplasmic reticulum (ER) stress-related protein expression such as phospho-PERK, caspase-12, Grp78, and CHOP. CONCLUSION: Pyridoxine preferentially induced severe cell death on nerve fiber in primary OC explants and markedly increased apoptotic cell death via mitochondria-mediated ER stress in VOT-33 cells.
Entities:
Keywords:
ER stress; VOT-33; auditory neuropathy; mitochondrial dysfunction; pyridoxine