Influência do envelhecimento na concentração de ácido hialurônico nas pregas vocais de ratas fêmeas

Abstract

The vibration of the vocal fold lamina propria is an important factor involved in vocal production and aging may change the amount of hyaluronic acid in the vocal fold leading to dysphonia. Aims:This study compares the concentration of hyaluronic acid in vocal folds of aged and young female rats. Study design: experimental. Materials and Methods:We used the vocal cords of 13 female rats divided into two groups: five aged rats and eight young ones. The tissue concentration of hyaluronic acid was determined using the fluorimetric method with the hyaluronic acid binding-protein coated on plates of enzyme-linked immunosorbent assay (ELISA), conjugated with biotin. Europium-labeled streptavidin was added and, after europium release with the use of enhancement solution, the final fluorescence was measured in a fluorometer. Results:We found the following concentrations of hyaluronic acid in vocal fold according to the group: 581.7 ng/mg in old female rats and 1275.6 ng/ mg in young female rats. Statistical analysis showed differences between groups. Conclusions:The vocal folds of old female rats have a lower concentration of hyaluronic acid when compared to such concentration on the vocal folds of young female rats. Braz J Otorhinolaryngol. 2012;78(3):14-8. BJORL ORIGINAL ARTICLE

Effect of Testosterone on the Thyroarytenoid Muscle and Lamina Propria of Female Rat Vocal Folds

“…The animals were aged 9 weeks and had a body weight of approximately 220 g. Sample size calculation was performed according to the Experimental Design Assistent of the National Centre for Replacement, Refinement & Reduction of Animals in Research (NC3Rs). Data from a prior study by our team on HA concentration in female rat VF were utilized, with a mean difference of 400 ng/mg, a standard deviation (SD) of 320 ng/mg, and an effect size (Cohen's d) of 1.25 5 . Using an alpha level of 0.05 and a power of 0.80, assuming an independent samples two‐sided t ‐test, the sample size calculation recommended 12 animals per group.…”

“…Data from a prior study by our team on HA concentration in female rat VF were utilized, with a mean difference of 400 ng/mg, a standard deviation (SD) of 320 ng/mg, and an effect size (Cohen's d) of 1.25. 5 Using an alpha level of 0.05 and a power of 0.80, assuming an independent samples two-sided t-test, the sample size calculation recommended 12 animals per group. In line with the principle of animal reduction, the ethics committee advised a 25% reduction in the control group.…”

“…For the measurement of HA, a non-competitive Enzyme-Linked Immunosorbent (ELISA) fluorometric method was employed. 5,28 This method is a direct, sensitive, and specific measurement technique that is not influenced by the presence of other glycosaminoglycans. A total of 21 VFs were used, including 12 from the experimental group and 9 from the control group.…”

“…4 The lamina propria (LP) of the female VF contains greater amount of hyaluronic acid (HA) compared to the male, likely as an adaptive response to the vibrational frequency. 5 The human larynx is a hormone-responsive organ, exhibiting variations in its cytology, for instance, during the menstrual cycle or due to fluctuations in thyroid hormone levels. 6,7 Receptors for both male and female sex hormones are present in the epithelium and LP of VF in both sexes, with a predominance in the macula flava.…”

“…The female vocal fold (VF) has a smaller vibrational length and volume, resulting in emitting a higher‐frequency glottal sound 4 . The lamina propria (LP) of the female VF contains greater amount of hyaluronic acid (HA) compared to the male, likely as an adaptive response to the vibrational frequency 5 …”