Effects of Hypothyroidism on the Extracellular Matrix of the Vocal Folds of Adult Female Rats.

Abstract

OBJECTIVE: The aim of the present study was to investigate the changes in the extracellular matrix of the vocal folds of female rats after induction of hypothyroidism. STUDY DESIGN: Prospective and experimental study. SETTING: Single tertiary center. METHODS: Female rats were divided into 2 groups: hypothyroid (after thyroidectomy and treatment with methimazole) and euthyroid (control). After 8-week experiment, the animals were euthanized and their vocal folds were removed. These were analyzed for the presence of collagen type I, collagen type III, and elastin using the enzyme-linked immunosorbent assay technique. An hyaluronan-binding protein isolated from bovine nasal cartilage was used to identify and isolate the hyaluronic acid for samples. RESULTS: The hypothyroid group presented significantly increased serum TSH concentrations (P = .0425) and significantly decreased serum T4 concentrations (P = .0024) compared to the control group. The concentration of type I collagen in the vocal folds of animals in the hypothyroid group was higher than in the control group (P = .0432), and an increase in the concentration of type III collagen was also observed (P = .0339). There was no statistically significant difference in the concentrations of elastin and hyaluronic acid between the groups. CONCLUSION: Hypothyroidism was able to cause changes in the extracellular matrix of the vocal folds of female rats. We found an increase in the concentration of type I collagen and type III collagen in the animals with hypothyroidism. There was no difference in the concentration of elastin and hyaluronic acid between the hypothyroid and control groups.