Cellular and Molecular Neurobiology
Author: Daniela Maria Chequer Charan | email: danichch92@gmail.com
Daniela Chequer Charan 1°, Kevin M. Boergens 2°, Wenqing Huang 3°, Maria Eugenia Gomez-Casati 4°, Ana Belen Elgoyhen 1°, Yunfeng Hua 3°, Mariano N. Di Guilmi 1°
1° Instituto de Investigaciones en Ingeniería Genética y Biología Molecular, Dr. Héctor N. Torres, INGEBI-CONICET, Buenos Aires, Argentina (C1428ADN)
2° Department of Physics, The University of Illinois at Chicago, USA
3° Department of Otolaryngology-Head and Neck Surgery, Shanghai Ninth Peoples Hospital, Shanghai, China
4° Instituto de Farmacología, Facultad de Medicina. Universidad de Buenos Aires. Argentina
Medial nucleus of the trapezoid body (MNTB) neurons are an integral component of the auditory brainstem circuitry involved in sound localization. In order to study how neural connectivity is refined post-hearing onset in this nucleus, we used serial block-face electron microscopy (SBEM) in mice at different ages (3 weeks, 6 and 18 months). We acquired circuitry-level data volumes of the MNTB neurons which allows a comprehensive neuro-morphological investigation of age-related changes. We found that the total number of MNTB cells is reduced with age. Moreover, the accumulation of age pigment on MNTB cells increased with age. The morphology of the presynaptic terminal, the calyx of Held, was heterogeneous independently of age but degenerated terminals were strongly evident in older animals along the tonotopic axes. Interestingly, poly-innervated MNTB cells were present not only in young but also in older animals being more frequent in the low frequency region. This last observation demonstrates that the multiple innervations of the MNTB is not only restricted to the developmental critical period, but that it is also present throughout life. As a conclusion, our data supports the notion that age-related hearing impairments can be in part a direct consequence of several morphological alterations at the brainstem level.