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Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure


In acquired sensorineural hearing loss, such as that produced by noise, drugs or aging, there can be massive loss of the synaptic connections between cochlear sensory cells and primary sensory neurons, without loss of the sensory cells themselves. Because the cell bodies and central projections of these cochlear neurons survive for months to years, there is a long therapeutic window in which to re-establish functional connections and improve hearing ability. Here we show in noise-exposed mice that local delivery of neurotrophin-3 (NT-3) to the round window niche, 24?hours after an exposure that causes an immediate loss of up to 50% loss of synapses in the cochlear basal region, can regenerate pre- and post-synaptic elements at the hair cell / cochlear nerve interface. This synaptic regeneration, as documented by confocal microscopy of immunostained cochlear sensory epithelia, was coupled with a corresponding functional recovery, as seen in the suprathreshold amplitude of auditory brainstem response Wave 1. Cochlear delivery of neurotrophins in humans is likely achievable as an office procedure via transtympanic injection, making our results highly significant in a translational context.


Suzuki J, Corfas G, Liberman MC. Round-window delivery of neurotrophin 3 regenerates cochlear synapses after acoustic overexposure. Scientific Reports. 2016;6:24907. doi:10.1038/srep24907.


About the author: Dr. Mordy Levy


Dr. Mordy Levy is possibly the only Canadian doctor to have graduated from three first professional doctorates in separate and distinct health care professions: Chiropractic Medicine (DC)-1997, Allopathic Medicine (MD)-2006, Naturopathic Medicine (ND)-2011, graduated Summa Cum Laude, from the prestigious National University of Health Sciences (Chicago, IL) and was the valedictorian of his graduating class.

Dr Levy's first undergraduate degree (BSc) was in Biology and Psychology from York University, graduated with Honours, and his second undergraduate degree (BMSc) was in Human Biology and Biomedical sciences from National University of Health Sciences (Chicago, IL)

Dr. Levy is a registered member in good standing with three distinct health professions in Ontario, namely the College of Chiropractors of Ontario, the College of Naturopaths of Ontario, in addition to the College of Homeopaths of Ontario.

Dr. Levy is board certified in Functional Medicine and is a professional member of the Institute of Functional Medicine, the Canadian Society of Orthomolecular Medicine, American College of Nutrition, in addition to the Ontario Association of Naturopathic Doctors, the Ontario Chiropractic Association and the Ontario Homeopathic Association.

Always an avid lifelong learner, Dr. Levy completed numerous postgraduate certifications in Functional Medicine, Clinical Nutrition, Medical Acupuncture, Homeopathic Medicine, in addition to Prolotherapy regenerative medicine. His clinical interests are in Neurological, Autoimmune, Hormonal and Gastrointestinal Dysfunctions.
On a personal noted: Dr. Levy enjoys spending time with his three boys, practicing TaeKwonDo and reviewing research articles.