The combined effects of trkB and trkC mutations on the innervation of the inner ear

作者：Bernd Fritzsch, Mariano Barbacid, Inmaculada Silos‐Santiago · 发表于：International Journal of Developmental Neuroscience · 年份：1998 · DOI：10.1016/s0736-5748(98)00043-4 · 被引用次数：62 · 研究领域：Axon Guidance and Neuronal Signaling、Nicotinic Acetylcholine Receptors Study、Neuroscience and Neuropharmacology Research

Previous research has demonstrated that only the two neurotrophins and their cognate receptors are necessary for the support of the inner ear innervation. However, detailed analyses of patterns of innervation in various combinations of neurotrophin receptor mutants are lacking. We provide here such an analysis of the distribution of afferent and efferent fibers to the ear in various combinations of neurotrophin receptor mutants using the lipophilic tracer Dil. In the vestibular system, trkC+/- heterozygosity aggravates the trkB-/- mutation effect and causes almost complete loss of vestibular neurons. In the cochlea innervation, various mutations are each characterized by specific topological absence of spiral neurons in Rosenthal's canal of the cochlea. trkC-/- mutation alone or in combination with trkB+/- heterozygosity causes absence of all basal turn spiral neurons and afferent fibers extend from the middle turn to the basal turn along inner hair cells with little or no contribution to outer hair cells. Both types of basal turn spiral neurons appear to develop and project via radial fibers to inner and, more sparingly, outer hair cells. Simple trkB-/- mutations show a reduction of fibers to outer hair cells in the apex and, less obvious, in the basal turn. Basal turn spiral neurons may be the only neurons present at birth in the cochlea of a trkB-/- mutant mouse combined with trkC+/- heterozygosity. In addition, the trkB-/- mutation combined with trkC+/- heterozygosity has...