Identification of Thyroid Hormone Receptors in the Human Larynx

Purpose: Thyroid hormone is essential for normal development, growth, and function of the majority of tissues. Among the many clinical signs associated with hypothyroidism, alterations in the voice may occur even in cases of mild thyroid failure, suggesting that the larynx is a target tissue for thyroid hormone. The objective of our study is to further understand the effects of thyroid hormone on the larynx by first identifying the presence and locations of its receptors. Methods: Two human cadaveric larynges (one male and one female) were harvested, formalin-fixed, and paraffin-embedded. Sections were immunostained with antibodies reactive with the two identified thyroid hormone receptors, TR-α and TR-β. The slides were examined under light microscopy. Results: Both male and female specimens revealed consistent patterns of staining for thyroid hormone receptors. The staining pattern for TR-α included the fibrous connective tissue of the lamina propria, the cartilage, and the glandular elements. The staining pattern for TR-β included the fibrous connective tissue of the lamina propria only. No receptors were identified in the respiratory mucosa or muscle. Conclusions: Thyroid hormone receptors are present in both the male and the female human larynx. These findings imply a role for thyroid hormone within the human larynx, through both TR-α and TR-β.