Heat stress affects the glucocorticoid receptor interaction with heat shock protein Hsp70 in the rat liver.

The association of glucocorticoid hormones receptor (GR) with heat shock protein Hsp70 in the liver cytosol of rats exposed to 41 degrees C whole body hyperthermic stress was examined by quantitative immunoblotting of the two proteins within immunopurified untransformed GR multiprotein complexes. The presence of Hsp70 in the rat liver GR heterocomplexes was confirmed, and 2-fold increase in the Hsp70 relative to the steroid binding protein content within the complexes was recorded 2 and 12 h after the stress. This increase exceeded the stress-induced elevation in the total cytoplasmic Hsp70 level, but could not be seen 24 h after the stress, when cytoplasmic Hsp70 returned to basal level. The results suggest that hyperthermic stress alters the composition of the rat liver untransformed GR heterocomplexes increasing the Hsp70 share.