A differential nuclear uptake and retention of 3H-androgens in the thyroids of baboons

Androgen-dependent expression of FcgammaRIIB2 by thyrocytes from patients with autoimmune Graves' disease: a possible molecular clue for sex dependence of autoimmune disease

Thyrocyte expression of HLA class I and class II antigens and related accessory molecules would convert these epithelial cells into functional antigen-presenting cells. Here we show that whereas normal thyrocytes express FcRn, Graves' disease thyrocytes also express FcgammaRIIB2. We further find that expression of FcgammaRIIB2, but not FcRn, is repressed by dihydrotestosterone. By mediating the uptake and transport of autoantibodies, we suggest that these IgG Fc receptors contribute in various ways to the onset and/or progression of autoimmune thyroid diseases. The androgen-mediated decrease of FcgammaRIIB2 expression in Graves' disease thyrocytes also provides a rationale for the predominant susceptibility of women to develop an autoimmune thyroid disease. Our findings open up a new prospect to autoimmunity, linking the role of the target organ to the sex dependence in autoimmune disease.

Androgen receptors in normal and pathological thyroids

The purpose of this study was to determine the presence of cytosolic and nuclear androgen receptors (AR) in both normal and nodular thyroid tissues from twelve women and six men. Samples of benign thyroid nodules and corresponding surrounding normal tissue were processed by the single saturation point assay, using [3H] R1881 ([3H] Methyltrienolone) at final concentration of 5 nM. The results show the presence of AR (cytosolic and/or nuclear) in all examined tissue samples. The nuclear AR content was higher (p less than 0.01) in normal rather than in nodular thyroid tissues. The same pattern was observed when nuclear AR were analyzed according to the sex. In addition, nuclear AR content was significantly (p less than 0.05) higher in normal thyroid tissue from men than from women. Our data suggest an androgen influence on thyroid tissue. If androgens are supposed to exert an antagonist role on estrogen actions also in thyroid tissue, the presence of higher nuclear AR concentration in the male rather than in the female normal thyroid may justify the lower incidence of thyroid diseases in men. Moreover, the lower AR levels found in male as well as in female nodular and goitrous tissues support the hypothesis that androgens may act with an antagonist mechanism on thyroid growth.