Structural changes and immunohistochemical localisation of epidermal growth factor receptor in the true vocal fold of female albino rats administered anabolic, androgenic steroids, and effects of anti-androgen therapy

Cellular and Molecular Effects of Steroid Sex Hormones on the Vocal Folds: A Scoping Review

OBJECTIVE

Steroid sex hormones (SSH) target cell nuclei to affect transcription. Although laryngeal tissue is theorized to be hormonally responsive, SSH receptor presence and cellular effects on the vocal folds are not well-established. A scoping review of this literature might inform future research.

DATA SOURCES

Medline, Embase, Scopus, and Web of Science were searched.

REVIEW METHODS

This review followed JBI and PRISMA-ScR Guidelines. Two independent reviewers screened each title/abstract and full text according to eligibility criteria. Exclusion criteria included primary outcomes based on subjective interpretation and secondary effects on the vocal folds (e.g., voice).

RESULTS

Three hundred and sixty one articles were screened at the title/abstract level, 83 at the full-text level, and 32 met inclusion criteria. Fourteen studies were performed in humans and 15 in animals; 3 were review articles. In studies directly examining receptors (n = 17), estrogen receptors (ER) were found in 10 of 15 studies, progesterone receptors (PR) in 6/10, and androgen receptors (AR) in 6/9. When the effects of SSH on vocal folds were studied (n = 16), estrogen had effects in 10/13, progesterone in 3/3, and androgens in 4/5. ER and PR were mostly identified in epithelium and fibroblasts of lamina propria (LP) while AR was found in muscle, lamina propria, and epithelium.

CONCLUSIONS

Existing evidence variably supports the presence of SSH receptors in vocal fold tissue; therefore, further clarification is needed. Estrogen and progesterone were most identified in mucosal tissue, where they decrease fibrosis and help maintain the epithelial barrier. Androgens appear to be pro-fibrotic in epithelium and hypertrophic in muscle. Laryngoscope, 2024.

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

OBJECTIVE

To analyze the effects of androgen therapy on the thyroarytenoid (TA) muscle, expression of androgen receptors (ARs) and hyaluronic acid (HA) concentration in the vocal folds (VFs) of adult female rats.

METHODS

Twenty-one adult female Wistar rats were divided into experimental and control groups. The experimental group received weekly intramuscular injections of nandrolone decanoate for 9 weeks. Following euthanasia and dissection of the VFs, histomorphometric analysis of the TA muscle, immunohistochemical evaluation of ARs, and measurement of HA concentration using the ELISA-like fluorimetric method were performed.

RESULTS

The experimental group exhibited a significantly larger mean fiber cross-sectional area in the TA muscle compared to the control group (434.3 ± 68.6 μm2 versus 305.7 ± 110.1 μm2; p = 0.029), indicating muscle hypertrophy. There was no significant difference in the number of muscle fibers. The experimental group showed higher expression of ARs in the lamina propria (62.0% ± 30.3% versus 22.0% ± 22.8%; p = 0.046) and in the TA muscle (45.0% ± 22.6% versus 18.3% ± 9.8%; p = 0.024). There was no significant difference in the concentration of HA.

CONCLUSION

Exposure of adult female rats to androgen therapy resulted in hypertrophy of the TA muscle and increased expression of ARs in the VFs. The TA muscle seems to be the primary target of testosterone action in the VF, and the up-regulation of ARs might contribute to the persistent deepening of the voice.

LEVEL OF EVIDENCE

NA Laryngoscope, 134:2316-2321, 2024.

The Use of Vocal Fold Injection Augmentation in a Transmasculine Patient Unsatisfied With Voice Following Testosterone Therapy and Voice Training

INTRODUCTION

There exist a cohort of transmasculine patients who remain dissatisfied with vocal function following testosterone therapy and voice training.

AIM

The objective of this case report was to describe the use of injection laryngoplasty in this cohort as an alternative to laryngeal framework surgery.

METHOD

A case report and literature review was undertaken.

RESULTS

Our case describes a 45-year-old transmasculine patient who remained unsatisfied with vocal pitch despite testosterone therapy and voice training. On initial presentation, the patient had fundamental frequency (fo) ranging from 70-344 Hz with a mean of approximately 135 Hz on reading, and 146 Hz in monologue. Injection augmentation of the vocal folds under local anesthesia with an injectable carboxymethylcellulose gel (prolaryn) was trialed. Following re-absorption of this, further injection was performed using autologous fat and subsequently a longer acting Calcium Hydroxyapatite injectable (Prolaryn Plus). This was followed by re-injection 1 year later. Patient satisfaction has been sustained throughout this period. Repeat acoustic evaluation in 2019 revealed a mean fo of 108 Hz on reading, 100 Hz in monologue, and a fo range of 85-134 Hz across these tasks.

CONCLUSION

This case report presents an alternative surgical intervention to supplement testosterone and voice training in transmasculine patients unsatisfied with vocal function.

The Effects of Menopause on Neuromuscular Parameters of the Rat Vocal Folds

OBJECTIVES/HYPOTHESIS

Menopause adversely affecs power and endurance of the limb muscles. However, despite clinical observations that menopause corresponds to negative changes of the voice, the direct effects of estrogen deprivation on the thyroarytenoid muscles are unknown. The purpose of this study was to investigate the effects of estrogen deprivation via ovariectomy on three neuromuscular parameters of the thyroarytenoid muscles using a rat model.

STUDY DESIGN

Animal model.

METHODS

Cryosections of vocal folds of 20 (10 control and 10 ovariectomized) female rats were stained to label neuromuscular junctions, fiber size, or parvalbumin levels using immunohistochemical techniques and compared between experimental groups.

RESULTS

The neuromuscular junctions, thyroarytenoid fiber sizes, and parvalbumin levels of the vocal folds were similar between experimental groups.

CONCLUSIONS

The loss of estrogen did not change neuromuscular parameters of the vocal folds of adult female rats; therefore, vocal changes within the outer vibratory layers of the vocal folds may primarily be responsible for clinically observed menopausal vocal changes.

LEVEL OF EVIDENCE

NA Laryngoscope, 131:1343-1348, 2021.

Case report: The long-term effects of anabolic steroids on the female voice over a 20-year period

Anabolic steroids and androgenic steroids (AAS) can have long-term effects on the female voice. These changes are clinically relevant since they are difficult to treat and therefore should be disclosed to patients using AAS or receiving androgenic steroid therapy.

Magnetic Resonance Imaging of the Vocal Folds in Women With Congenital Adrenal Hyperplasia and Virilized Voices

PURPOSE

Women with congenital adrenal hyperplasia (CAH) may develop a virilized voice due to late diagnosis or suboptimal suppression of adrenal androgens. Changes in the vocal folds due to virilization have not been studied in vivo. The purpose was to investigate if the thyroarytenoid (TA) muscle is affected by virilization and correlate findings to fundamental frequency (F0).

METHOD

A case-control study using magnetic resonance imaging and voice recordings. Four women with CAH with virilized voices (26-40 years), and 5 female and 4 male controls participated. Measurements of cross-sectional TA muscle area, vocal fold length, vocal tract length, and acoustic analyses of F0 were performed.

RESULTS

Women with CAH had larger cross-sectional TA muscle area than female control subjects and smaller than male controls. A significant negative correlation was found between TA muscle area and mean F0. The patients had a smaller physiological voice range than both female and male controls.

CONCLUSION

Data from our small study suggest that a larger TA muscle area is strongly associated with a lower F0 and thus the anatomical explanation for a female virilized voice, suggesting an androgen effect on the vocal folds. The findings from the present study need to be confirmed in a larger study.

Differential responses to steroid hormones in fibroblasts from the vocal fold, trachea, and esophagus

There is accumulating evidence that fibroblasts are target cells for steroids such as sex hormones and corticoids. The characteristics of fibroblasts vary among tissues and organs. Our aim in this study is to examine differences in responses to steroid hormones among fibroblasts from different cervicothoracic regions. We compared the actions of steroid hormones on cultured fibroblasts from the vocal folds, which are considered to be the primary target of steroid hormones, and the trachea and esophagus in adult male rats. Expression of steroid hormone receptors (androgen receptor, estrogen receptor α, and glucocorticoid receptor) was identified by immunofluorescence histochemistry. Androgen receptor was much more frequently expressed in fibroblasts from the vocal fold than in those from the trachea and esophagus. Cell proliferation analysis showed that administration of testosterone, estradiol, or corticosterone suppressed growth of all 3 types of fibroblasts. However, mRNA expression for extracellular matrix-associated genes, including procollagen I and III and elastin, and hyaluronic acid synthase I was elevated only by addition of testosterone to fibroblasts from the vocal fold. These results indicate that each steroid hormone exerts region-specific effects on cervicothoracic fibroblasts with different properties through binding to specific receptors.