The primate thyroid gland contains receptors for androgens

The gonadal steroids have long been known to modulate thyroid function. Most studies suggest that the gonadal steroids act indirectly through the hypothalamic-pituitary axis to modulate thyroid function. The following studies were conducted to determine whether there are receptors for androgens in the thyroid itself. Cytosols from male and female euthyroid patients were analyzed for the presence of androgen with the synthetic analog methyltrienolone ([³H]R1881). No evidence of androgen receptors was found in any of the cytosols prepared from female patients. In all males studied, androgen receptors were found in concentrations ranging from 100-150 fmol/10 mg DNA for the cytosols and from 690-2800 fmol/10 mg DNA for the nuclear extracts. The receptors had a dissociation constant (K_d) of approximately 5-10 × 10^-10 m for the cytosol and approximately 10-15 × 10^-10 m for the nuclear extracts. In addition to the human studies, studies in baboons were conducted to determine the possible cell type which might contain receptors for androgens. Male and female baboons were injected with [³H] dihydrotestosterone and killed between 1 and 11/2 h later. The thyroids were removed and processed for autoradiography. In autoradiograms from animals injected with [³H]dihydrotestosterone, nuclear localization of radioactivity was found in virtually all of the follicular cells. Also, label was found overlying the colloid, with heaviest labeling near the cells. These data suggest that there may be direct actions of androgens on follicular cells.