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

Abstract

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. Prospective and experimental study. Single tertiary center. 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. 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. 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.