IMMUNOREACTIVE TSH CELLS IN THE PITUITARY OF FEMALE MIDDLE-AGED RATS AFTER TREATMENT WITH ESTRADIOL OR CALCIUM

The pituitary TSH cell structure of middle-aged (14-month-old) female Wistar rats chronically treated with estradiol dipropionate (EDP), cal cium glucoheptonate (Ca) or with the combination of both was studied. TSH-producing cells were examined in the pituitary pars distalis using rabbit anti-rat beta-thyrotropin (TSH) serum and peroxidase-antiperox idase immunohistochemistry. A stereological method for the determinati on of morphometric changes of the volume of TSH cells and nuclei as we ll as of their number and relative volume densities was used. All exam ined morphometric parameters in treated animals showed a significant d ecrease in comparison with immunoreactive TSH cells of the controls; t he most significant decrease was observed in EDP-treated rats. These r esults together with structural features of immunoreactive TSH cells i n the pituitary of middle-aged rats after chronic application of EDP o r Ca indicate that both compounds inhibit these cells.