Glucocorticoid receptor-Hsp90 interaction in the liver cytosol of cadmium-intoxicated rats

The influence of cadmium on the rat liver glucocorticoid receptor (GR) binding capacity, on the cytosolic level of 90 kDa heat shock protein (Hsp90), and on the association of the two proteins was investigated. The results showed that the mode of metal application led to diverse alterations in hormone binding to the GR. Reduction of the GR binding capacity observed after in vitro treatment was proportional to the applied metal concentrations. In animals administered different doses of cadmium, GR binding capacity was not reduced, except in those that received the highest dose. A concomitant elevation of Hsp90 level was detected both in the cytosol and within the GR untransformed heterocomplexes. The results suggest that cadmium-induced reduction of the GR binding capacity seen in vitro was prevented in intact animals by the elevated level of Hsp90 within the GR heterocomplexes.