IN-VITRO EFFECTS OF SODIUM SELENITE ON NUCLEAR 3,5,3'-TRIIODOTHYRONINE (T-3) RECEPTOR GENE-EXPRESSION IN RAT PITUITARY GH(4)C(1) CELLS

The present study was undertaken in order to investigate the effects o f sodium selenite on: 1. The growth of rat pituitary GH(4)C(1) cells; 2. The nuclear T-3 receptor gene expression; 3. The cytoplasmic protei n phosphorylation; and 4. The prolactin secretion in rat pituitary GH( 4)C(1) cell line. Sodium selenite (up to 2.5 mu M) has no inhibitory e ffect on GH(4)C(1) cell proliferation as well as the prolactin secreti on. On the other hand, 0.5 mu M sodium selenite significantly decrease s the rate of mRNA synthesis and/or degradation of both, the al form o f the T-3 receptor (TR alpha 1) and the alpha 2 isoform of the T-3 rec eptor. At 1 mu M of sodium selenite, significant changes in the electr ophoretic profile of low molecular mass cytoplasmic proteins were foun d, moreover, sodium selenite (1 mu M) also considerably affects phosph orylation of a higher molecular mass proteins. The results based on th e in vitro experiments suggest that sodium selenite may affect specifi c processes at the pretranslational level as well as it may also take part in processes of posttranslational modification of protein(s), the cell vitality and the cell growth remaining unchanged.