Age-related neurochemical changes in the rhesus macaque superior olivary complex
Article first published online: 20 DEC 2013
Copyright © 2013 Wiley Periodicals, Inc.
Journal of Comparative Neurology
Volume 522, Issue 3, pages 573–591, 15 February 2014
How to Cite
Gray, D. T., Engle, J. R. and Recanzone, G. H. (2014), Age-related neurochemical changes in the rhesus macaque superior olivary complex. J. Comp. Neurol., 522: 573–591. doi: 10.1002/cne.23427
- Issue published online: 20 DEC 2013
- Article first published online: 20 DEC 2013
- Accepted manuscript online: 12 AUG 2013 06:01AM EST
- Manuscript Accepted: 3 JUL 2013
- Manuscript Revised: 6 MAR 2013
- Manuscript Received: 13 DEC 2012
- National Institute on Aging . Grant Numbers: R21AG024372 , R01AG034137
- National Institute of Deafness and Other Cummunication Disorders . Grant Number: T32DC008072
Positive immunoreactivity to the calcium-binding protein parvalbumin (PV) and nitric oxide synthase NADPH-diaphorase (NADPHd) is well documented within neurons of the central auditory system of both rodents and primates. These proteins are thought to play roles in the regulation of auditory processing. Studies examining the age-related changes in expression of these proteins have been conducted primarily in rodents but are sparse in primate models. In the brainstem, the superior olivary complex (SOC) is crucial for the computation of sound source localization in azimuth, and one hallmark of age-related hearing deficits is a reduced ability to localize sounds. To investigate how these histochemical markers change as a function of age and hearing loss, we studied eight rhesus macaques ranging in age from 12 to 35 years. Auditory brainstem responses (ABRs) were obtained in anesthetized animals for click and tone stimuli. The brainstems of these same animals were then stained for PV and NADPHd reactivity. Reactive neurons in the three nuclei of the SOC were counted, and the densities of each cell type were calculated. We found that PV and NADPHd expression increased with both age and ABR thresholds in the medial superior olive but not in either the medial nucleus of the trapezoid body or the lateral superior olive. Together these results suggest that the changes in protein expression employed by the SOC may compensate for the loss of efficacy of auditory sensitivity in the aged primate. J. Comp. Neurol. 522:573–591, 2014. © 2013 Wiley Periodicals, Inc.