title: A permeability barrier surrounds taste buds in lingual epithelia.
abstract: Epithelial tissues are characterized by specialized cell-cell junctions, typically localized to the apical regions of cells. These junctions are formed by interacting membrane proteins and by cytoskeletal and extracellular matrix components. Within the lingual epithelium, tight junctions join the apical tips of the gustatory sensory cells in taste buds. These junctions constitute a selective barrier that limits penetration of chemosensory stimuli into taste buds (Michlig et al. J Comp Neurol 502: 1003-1011, 2007). We tested the ability of chemical compounds to permeate into sensory end organs in the lingual epithelium. Our findings reveal a robust barrier that surrounds the entire body of taste buds, not limited to the apical tight junctions. This barrier prevents penetration of many, but not all, compounds, whether they are applied topically, injected into the parenchyma of the tongue, or circulating in the blood supply, into taste buds. Enzymatic treatments indicate that this barrier likely includes glycosaminoglycans, as it was disrupted by chondroitinase but, less effectively, by proteases. The barrier surrounding taste buds could also be disrupted by brief treatment of lingual tissue samples with DMSO. Brief exposure of lingual slices to DMSO did not affect the ability of taste buds within the slice to respond to chemical stimulation. The existence of a highly impermeable barrier surrounding taste buds and methods to break through this barrier may be relevant to basic research and to clinical treatments of taste.
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida; and.
authors.forename: Robin
authors.initials: R
authors.lastname: Dando
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida; and.
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Pereira
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida; and.
authors.forename: Mani
authors.initials: M
authors.lastname: Kurian
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida; and.
authors.forename: Rene
authors.initials: R
authors.lastname: Barro-Soria
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida; and Program in Neuroscience, University of Miami, Miami, Florida.
authors.forename: Nirupa
authors.initials: N
authors.lastname: Chaudhari
authors.affiliation: Department of Physiology and Biophysics, Miller School of Medicine, University of Miami, Miami, Florida; and Program in Neuroscience, University of Miami, Miami, Florida sroper@med.miami.edu.
authors.forename: Stephen D
authors.initials: SD
authors.lastname: Roper
mesh_terms: D000818:Animals; D004121:Dimethyl Sulfoxide / Q000494:pharmacology; D004798:Enzymes / Q000378:metabolism; D004847:Epithelial Cells / Q000187:drug effects / Q000378:metabolism*; D005452:Fluoresceins / Q000737:chemistry / Q000378:metabolism; D005456:Fluorescent Dyes / Q000737:chemistry / Q000378:metabolism; D008564:Membrane Potentials; D008810:Mice, Inbred C57BL; D008970:Molecular Weight; D010539:Permeability; D012997:Solvents / Q000494:pharmacology; D013268:Stimulation, Chemical; D013649:Taste; D013650:Taste Buds / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D019108:Tight Junctions / Q000187:drug effects / Q000378:metabolism*; D014059:Tongue / Q000294:innervation*
chemical_list: D004798:Enzymes; D005452:Fluoresceins; D005456:Fluorescent Dyes; D012997:Solvents; C069306:5-chloromethylfluorescein; D004121:Dimethyl Sulfoxide
keywords: DMSO; barrier; lingual epithelium; taste