Abstract # 13236 Event # 147:

Scheduled for Friday, August 10, 2018 02:45 PM-03:00 PM: (Chula Vista ) Oral Presentation


AGE-RELATED COCHLEAR HISTOPATHOLOGIES IN OLD-WORLD AND NEW-WORLD PRIMATES: THE RHESUS MACAQUE (MACACA MULATTA) AND THE COMMON MARMOSET (CALLITHRIX JACCHUS)

M. Liberman1,3, C. Ross2, S. Tardif4, G. Recanzone5, T. Hackett6, R. Ramachandran6, T. Moore7 and M. D. Valero1,8
1Massachusetts Eye and Ear , 243 Charles St, Boston, Massachusetts 02114, USA, 2Department of Science and Mathematics, Texas A&M University San Antonio, San Antonio TX 78224, 3Harvard Medical School, 4Southwest National Primate Research Center, San Antonio, TX , 5Center for Neuroscience and Department of Neurobiology, Physiology and Behavior, University of California at Davis., 6Department of Hearing and Speech Sciences, Vanderbilt University Medical Center, Nashville, TN, 7Department of Anatomy and Neurobiology, Boston University School of Medicine, Boston, MA, 8Akouos, Inc.
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      Recent data suggest that cochlear synapses are more vulnerable than hair cells in aging rodents and humans. Therapies aimed to prevent, reduce, or reverse cochlear pathologies are under development, and NHPs represent an important translational model. Here, we describe aging phenotypes in macaques (Macaca mulatta; maximum lifespan of 40yrs) and marmosets (Callithrix jacchus; maximum lifespan of 22yrs). We evaluated 5 young (mean=7.6 yrs), 4 middle-aged (13.3yrs), and 5 old (24.5yrs) macaque ears from Vanderbilt, Boston University, and U.C. Davis, and 8 young (3yrs) and 10 old (16yrs) marmoset ears from SNPRC. Cochlear histological assessments in young monkeys were used as comparators to quantify the effects of aging on the survival of hair cells and cochlear synapses. Aging macaques were missing up to 36% of their outer hair cells (OHCs) in high-frequency regions and fewer than 15% of inner hair cells (IHCs). However, surviving IHCs were missing up to 50% of their afferent synapses. Some aging marmosets had significant OHC loss (?85% in high-frequency regions). Additionally, as many as 60% of afferent synapses were lost on surviving IHCs of aged marmoset cochleas. In both primate species, there were synaptopathic regions with little or no OHC loss. These data provide further evidence that synapses are the most vulnerable element in the aging primate cochlea and are therefore an important target for intervention strategies.