Presence of a functional TSH receptor on human erythrocytes

The presence of thyrotropin receptors (TSHR) has been reported in some extrathyroidal tissues but its physio-pathological role still remains unclear. TSH (seems to) affects the human erythrocytes Na+/K+-ATPase in vitro, however receptors on erythrocytes have not yet been described. In this work the effect of recombinant human TSH (rhTSH) on sites number and activity of erythrocyte Na+/K+-ATPase was investigated in a group of thyroidectomized patient enrolled for rhTSH test. As detected by 3H-ouabain binding, rhTSH administration induced a significant increase in the number of sites (p = 0.005) and in the Kd (p = 0.006) of Na+/K+-ATPase. rhTSH did not induce significant difference in Na+/K+-ATPase activity measured by 86Rb uptake. 125I-TSH binding studies and Western blotting data showed the existence of TSHR in the erythrocytes of healthy donors. In conclusion The TSH action on Na+/K+-ATPase of human erythrocytes can be explained by the presence of TSHR