Altered cochlear innervation in developing and mature naked and Damaraland mole rats. Issue 14 (25th March 2019)

• Record Type: Journal Article
• Authors: Barone, Catherine M.; Douma, Sytse; Reijntjes, Daniël O. J.; Browe, Brigitte M.; Köppl, Christine; Klump, Georg; Park, Thomas J.; Pyott, Sonja J.
• Is Part Of: Journal of comparative neurology. Volume 527:Issue 14(2019)
• Page Start: 2302
• Page End: 2316
• Publication Date: 2019-03-25
• Subjects: auditory -- BK channels -- cochlea -- development -- gerbil -- inner and outer hair cells -- inner ear -- lateral and medial efferent olivocochlear innervation -- mice -- presynaptic afferent ribbons -- RRID: AB_11150471 -- RRID: AB_143157 -- RRID: AB_2200400 -- RRID: AB_2313725 -- RRID: AB_2534069 -- RRID: AB_2535810 -- RRID: AB_399431 -- RRID: AB_90710 -- tonotopy; Comparative neurobiology -- Periodicals; Neurology -- Periodicals; 616
• DOI: 10.1002/cne.24682
• Languages: English
• ISSNs: 0021-9967

Abstract

Abstract: Compared to many other rodent species, naked mole rats ( Heterocephalus glaber ) have elevated auditory thresholds, poor frequency selectivity, and limited ability to localize sound. Because the cochlea is responsible for encoding and relaying auditory signals to the brain, we used immunofluorescence and quantitative image analysis to examine cochlear innervation in mature and developing naked mole rats compared to mice ( Mus musculus ), gerbils ( Meriones unguiculatus ), and Damaraland mole rats ( Fukomys damarensis ), another subterranean rodent. In comparison to mice and gerbils, we observed alterations in afferent and efferent innervation as well as their patterns of developmental refinement in naked and Damaraland mole rats. These alterations were, however, not always shared similarly between naked and Damaraland mole rats. Most conspicuously, in both naked and Damaraland mole rats, inner hair cell (IHC) afferent ribbon density was reduced, whereas outer hair cell afferent ribbon density was increased. Naked and Damaraland mole rats also showed reduced lateral and medial efferent terminal density. Developmentally, naked mole rats showed reduced and prolonged postnatal reorganization of afferent and efferent innervation. Damaraland mole rats showed no evidence of postnatal reorganization. Differences in cochlear innervation specifically between the two subterranean rodents and more broadly among rodents provides insight into the cochlear mechanisms that enhance frequency sensitivity and sound localization, maturation of the auditory system, and the evolutionary adaptations occurring in response to subterranean environments. Abstract : We examined patterns of innervation in the cochleae from naked mole rats (subterranean rodents with poor hearing) compared to mice (sensitive high frequency hearers), gerbils (sensitive low frequency hearers), and Damaraland mole rats (closely related subterranean rodents) to identify the peripheral mechanisms that contribute to hearing sensitivity and sound localization.