title: BDNF is required for taste axon regeneration following unilateral chorda tympani nerve section.
abstract: Taste nerves readily regenerate to reinnervate denervated taste buds; however, factors required for regeneration have not yet been identified. When the chorda tympani nerve is sectioned, expression of brain-derived neurotrophic factor (BDNF) remains high in the geniculate ganglion and lingual epithelium, despite the loss of taste buds. These observations suggest that BDNF is present in the taste system after nerve section and may support taste nerve regeneration. To test this hypothesis, we inducibly deleted Bdnf during adulthood in mice. Shortly after Bdnf gene recombination, the chorda tympani nerve was unilaterally sectioned causing a loss of both taste buds and neurons, irrespective of BDNF levels. Eight weeks after nerve section, however, regeneration was differentially affected by Bdnf deletion. In control mice, there was regeneration of the chorda tympani nerve and taste buds reappeared with innervation. In contrast, few taste buds were reinnervated in mice lacking normal Bdnf expression such that taste bud number remained low. In all genotypes, taste buds that were reinnervated were normal-sized, but non-innervated taste buds remained small and atrophic. On the side of the tongue contralateral to the nerve section, taste buds for some genotypes became larger and all taste buds remained innervated. Our findings suggest that BDNF is required for nerve regeneration following gustatory nerve section.
authors.affiliation: Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
authors.forename: Lingbin
authors.initials: L
authors.lastname: Meng
authors.affiliation: Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40292, USA.
authors.forename: Tao
authors.initials: T
authors.lastname: Huang
authors.affiliation: Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: Chengsan
authors.initials: C
authors.lastname: Sun
authors.affiliation: Department of Psychology, University of Virginia, Charlottesville, VA 22904, USA.
authors.forename: David L
authors.initials: DL
authors.lastname: Hill
authors.affiliation: Department of Anatomical Sciences and Neurobiology, University of Louisville School of Medicine, Louisville, KY 40292, USA. Electronic address: rfkrim01@louisville.edu.
authors.forename: Robin
authors.initials: R
authors.lastname: Krimm
mesh_terms: D000818:Animals; D019208:Brain-Derived Neurotrophic Factor / Q000235:genetics / Q000378:metabolism*; D002814:Chorda Tympani Nerve / Q000293:injuries*; D004195:Disease Models, Animal; D004965:Estrogen Antagonists / Q000494:pharmacology; D005155:Facial Nerve Diseases / Q000473:pathology*; D005260:Female; D007839:Functional Laterality / Q000502:physiology*; D005786:Gene Expression Regulation / Q000187:drug effects / Q000235:genetics; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D008822:Mice, Transgenic; D009416:Nerve Regeneration / Q000502:physiology*; D013629:Tamoxifen / Q000494:pharmacology; D013649:Taste / Q000502:physiology*; D013650:Taste Buds / Q000473:pathology; D013997:Time Factors; D014404:Tubulin / Q000378:metabolism; D001616:beta-Galactosidase / Q000378:metabolism
chemical_list: D019208:Brain-Derived Neurotrophic Factor; D004965:Estrogen Antagonists; D014404:Tubulin; C462941:beta3 tubulin, mouse; D013629:Tamoxifen; D001616:beta-Galactosidase
keywords: BDNF; Nerve regeneration; Neurotrophins; Sensory; Taste; Taste bud