title: Mechanisms of taste bud cell loss after head and neck irradiation.
abstract: Taste loss in human patients following radiotherapy for head and neck cancer is a common and significant problem, but the cellular mechanisms underlying this loss are not understood. Taste stimuli are transduced by receptor cells within taste buds, and like epidermal cells, taste cells are regularly replaced throughout adult life. This renewal relies on progenitor cells adjacent to taste buds, which continually supply new cells to each bud. Here we treated adult mice with a single 8 Gy dose of x-ray irradiation to the head and neck, and analyzed taste epithelium at 1-21 d postirradiation (dpi). We found irradiation targets the taste progenitor cells, which undergo cell cycle arrest (1-3 dpi) and apoptosis (within 1 dpi). Taste progenitors resume proliferation at 5-7 dpi, with the proportion of cells in S and M phase exceeding control levels at 5-6 and 6 dpi, respectively, suggesting that proliferation is accelerated and/or synchronized following radiation damage. Using 5-bromo-2-deoxyuridine birthdating to identify newborn cells, we found that the decreased proliferation following irradiation reduces the influx of cells at 1-2 dpi, while the robust proliferation detected at 6 dpi accelerates entry of new cells into taste buds. In contrast, the number of differentiated taste cells was not significantly reduced until 7 dpi. These data suggest a model where continued natural taste cell death, paired with temporary interruption of cell replacement, underlies taste loss after irradiation.
authors.affiliation: Department of Cell and Developmental Biology, School of Medicine, Rocky Mountain Taste and Smell Center, Graduate Program in Cell Biology, Stem Cells and Development, and Department of Craniofacial Biology, School of Dental Medicine, University of Colorado, Anschutz Medical Campus, Aurora, CO 80045, USA.
authors.forename: Ha M
authors.initials: HM
authors.lastname: Nguyen
authors.forename: Mary E
authors.initials: ME
authors.lastname: Reyland
authors.forename: Linda A
authors.initials: LA
authors.lastname: Barlow
mesh_terms: D000818:Animals; D016923:Cell Death / Q000502:physiology; D002454:Cell Differentiation / Q000528:radiation effects; D004307:Dose-Response Relationship, Radiation; D005260:Female; D006257:Head / Q000528:radiation effects*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D009333:Neck / Q000528:radiation effects*; D058953:Neural Stem Cells / Q000473:pathology* / Q000528:radiation effects*; D013650:Taste Buds / Q000473:pathology* / Q000528:radiation effects*