Age-associated changes in the expression and deposition of vocal fold collagen and hyaluronan.
OBJECTIVE
We investigated age-associated changes in the expression and deposition of collagen and hyaluronan (hyaluronic acid; HA) in aged vocal folds.


METHODS
Thirty Sprague-Dawley rats were involved in this study. For gene expression analyses, 15 animals were divided into 3 age groups of young (2 month), adult (9 month), and elderly (18 month) rats. Real-time polymerase chain reaction testing was used to quantify the messenger RNA expression of procollagen types I and III, matrix metalloproteinases 2 and 9, and HA synthases 1, 2, and 3. The remaining 15 animals were divided into 3 similar age groups and underwent histologic analyses designed to investigate age-associated changes in the deposition of collagen and HA.


RESULTS
The results revealed down-regulated expression of procollagen types I and III, matrix metalloproteinases 2 and 9, and HA synthases 1, 2, and 3 in adult and elderly vocal folds, compared to young vocal folds. Histologically, staining of collagen was dense in the vocal folds of adult and elderly rats, and HA was less dense in the vocal folds of adult and elderly rats than in young rats.


CONCLUSIONS
A slowdown in the expression of procollagens and matrix metalloproteinases was associated with dense collagen in aged vocal folds, as observed in elderly humans. A similar decrease in the expression of genes that code for HA synthase was consistent with a low density of extracellular matrix HA in the vocal folds of elderly rats.
Ohno
Tsunehisa
T
Department of Otolaryngology, Vanderbilt University Bill Wilkerson Center for Otolaryngology and Communication Sciences, Nashville, Tennessee 37232-4480, USA.
Hirano
Shigeru
S
Rousseau
Bernard
B
D000375:Aging / Q000502:physiology*; D000818:Animals; D003094:Collagen / Q000235:genetics / Q000378:metabolism*; D015536:Down-Regulation / Q000502:physiology; D005786:Gene Expression Regulation / Q000502:physiology*; D014453:Glucuronosyltransferase / Q000378:metabolism; D000076002:Hyaluronan Synthases; D006820:Hyaluronic Acid / Q000235:genetics / Q000378:metabolism*; D008297:Male; D020782:Matrix Metalloproteinases / Q000235:genetics / Q000378:metabolism; D011446:Prospective Studies; D051381:Rats; D017207:Rats, Sprague-Dawley; D014827:Vocal Cords / Q000378:metabolism*
D006820:Hyaluronic Acid; D003094:Collagen; D014453:Glucuronosyltransferase; D000076002:Hyaluronan Synthases; D020782:Matrix Metalloproteinases