The effects of stress on the association between hsp70 and the glucocorticoid receptor in rainbow trout.

The purpose of this study was to characterize the association between hepatic heat shock protein 70 (hsp70) and the glucocorticoid receptor in rainbow trout that were exposed to heat stress, cortisol, and beta-naphthoflavone. This study is the first to document that the glucocorticoid receptor complex in rainbow trout hepatic tissues contains hsp70. Heat stress significantly increased levels of total cellular hsp70, and by discerning the association of hsp70 with the glucocorticoid receptor, we demonstrated that heat stress significantly increased the amount of hsp70 not bound to the glucocorticoid receptor, while significantly decreasing the amount of hsp70 bound to the glucocorticoid receptor. By calculating the ratio of hsp70 bound to the glucocorticoid receptor, to the total number of glucocorticoid receptors, stress (heat stress and cortisol-treatment) promoted the association of hsp70 with the glucocorticoid receptor. These findings demonstrate a functional and structural link between hsp70 and the glucocorticoid receptor in rainbow trout, and raise questions regarding the existence of a complex, interrelated stress response that spans all levels of biological organization within the whole animal.