Sufficient vocal fold superficial hydration is indispensable to maintain normal vocal function and protect vocal fold epithelium against invasion of pathogenic agents. Vocal fold surface hydration is probably regulated by its electrophysiological properties. We hypothesized that the tight junction (TJ)-related paracellular barrier contributes to the maintenance of those properties. Therefore, we investigated the gene expression and distribution patterns in vocal fold epithelium of TJ-associated components, occludin and ZO-1, and TJ-related paracellular permeability with or without the challenge of a permeability-augmenting agent, histamine. Freshly excised ovine larynges were obtained from a local abattoir. The gene expression and distribution of TJ markers were explored at mRNA and protein levels, respectively, via reverse transcriptase polymerase chain reaction (RT-PCR) and immunostaining. TJ-related paracellular permeabilities to charged and non-charged solutes were measured in an Ussing system with or without histamine challenge. Histamine's effect on the gene expression of TJ markers was also assessed through real time RT-PCR. The gene expression of both TJ markers was detected in native ovine vocal fold epithelium with distinct distribution patterns at their corresponding protein level. Luminal histamine treatment (40mM~100mM) significantly augmented the TJ-related paracellular permeabilities to charged and non-charged solutes, as manifested by reduction in transepithelial resistance (TER) (N=72, p<0.01) and increased penetration of protein tracer (N=35, p<0.001), respectively, in a time-, and dose-dependent fashion. Also these changes caused by histamine were accompanied by a significant downregulation of gene expression for both TJ markers, occludin (N=20, p=0.004<0.05) and ZO-1 (N=44, p=0.036<0.05). The present study demonstrates the involvement of TJ-related paracellular barrier in the maintenance of bioelectrical asymmetry across vocal fold epithelium. The detection of TJ markers indicates the existence of typical TJ components in stratified vocal fold epithelium. The responsiveness of TJ-related paracellular permeabilities and gene expression of TJ markers to histamine highlights the functional significance of this TJ-equivalent system to the maintenance of bioelectrical properties of vocal fold epithelium, a type of non-keratinized, stratified, squamous epithelium. In conclusion, TJ-related paracellular permeability exists and contributes to the bioelectrical homeostasis of the epithelium covering the vocal fold, which, in turn, regulates the vocal fold superficial hydration.

Last modified

• 09/19/2018

Creator

• Qianru Zhang

DOI

• https://doi.org/10.21985/N2ZT74

Subject

• Communication Sciences and Disorders - Speech and Language Pathology

Keyword

• HISTAMINE
• VOCAL FOLD
• VOICE
• EPITHELIUM
• TIGHT JUNCTION

Date created

• 2008-11-21

Resource type

• Dissertation

Rights statement

• In Copyright