EFFECT OF SELENITE AND SELENATE ON RAT-LIVER NUCLEAR 3,5,3'-TRIIODOTHYRONINE (T-3) RECEPTOR

The present study was undertaken to investigate the effects of selenite (Se-IV) or selenate (Se-VI) on nuclear T-3 receptors of rat liver. Selenite at 0.1 mu M (p < 0.01) inhibited the T-3 specific binding to rat liver nuclear receptors. The specific binding of the T-3 receptor was fully restored when even 1.0 mu M selenite was separated from the T-3 receptor by gel filtration. No inhibitory effect of selenite (up to 100 mu M) on the T-3 binding to nuclear receptor was found in the presence of 1.0 mM dithiothreitol. The rate of dissociation of the T-3-nuclear receptor complex was effectively increased by 0.1 mu M selenite. Selenate up to 1 mM as well as sulfite or sulfate up to 0.1 mM did not exert an inhibitory effect on T-3 receptors. The results based on the in vitro experiments suggest that the selenium in the form of selenite may reversibly affect the T-3 binding on the receptor molecule.