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Raised intensity phonation compromises vocal fold epithelial barrier integrity

Authors

  • Bernard Rousseau PhD,

    Corresponding author
    1. Department of Otolaryngology, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee
    2. Department of Hearing and Speech Sciences, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee
    • Vanderbilt University Bill Wilkerson Center, Departments of Otolaryngology and Hearing and Speech Sciences, 1313 21st Avenue South, Room 602, Nashville, TN 37232-4480
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  • Atsushi Suehiro MD, PhD,

    1. Department of Otolaryngology, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee
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  • Nicholas Echemendia BS,

    1. Department of Otolaryngology, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee
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  • Mahalakshmi Sivasankar PhD

    1. Department of Speech, Language, and Hearing Sciences, Purdue University, West Lafayette, Indiana, U.S.A.
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  • This study was performed in accordance with the PHS Policy on Humane Care and Use of Laboratory Animals, the NIH Guide for the Care and Use of Laboratory Animals, and the Animal Welfare Act (7 U.S.C. et seq.); the animal use protocol was approved by the Institutional Animal Care and Use Committee (IACUC) of Vanderbilt University Medical Center.

Abstract

Objectives/Hypothesis:

We investigated the hypothesis that 30 minutes of raised intensity phonation alters transcript levels of vocal fold intercellular tight junction proteins and disrupts the vocal fold epithelial barrier.

Study Design:

Prospective animal study.

Methods:

Eighteen New Zealand white breeder rabbits were randomly assigned to receive 30 minutes of raised intensity phonation or approximation of the vocal folds without phonation. Quantitative polymerase chain reaction (qPCR) was used to investigate transcript levels of the epithelial intercellular tight junction proteins, occludin and zonula occludin-1 (ZO-1), and the adherens junction proteins β-catenin and E-cadherin. Structural alterations to the vocal fold epithelium were further examined by scanning electron microscopy (SEM) and transmission electron microscopy (TEM).

Results:

Mann-Whitney U revealed significantly decreased occludin (P = .016) and β-catenin (P = .016) gene expression from rabbits undergoing raised intensity phonation compared with control. There were no significant differences in Z0-1 and E-cadherin gene expression between groups (P > .025). SEM revealed significant obliteration, desquamation, and evidence of microhole formation in rabbit vocal folds exposed to raised intensity phonation compared with control, whereas TEM revealed dilated intercellular morphology between groups.

Conclusions:

Results provide support for the hypothesis that a transient episode of raised intensity phonation alters transcript levels of vocal fold intercellular tight junction proteins and disrupts integrity of the epithelial barrier. The loss of barrier integrity may have significant consequences on epithelial defenses and compromise protection of the underlying mucosa from damage secondary to prolonged vibration exposure.

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