HYPERTHERMIC STRESS AFFECTS GLUCOCORTICOID RECEPTOR-MEDIATED TRANSCRIPTION IN RAT-LIVER

Binding capacity of the cytoplasmic and nuclear glucocorticoid recepto r (GR) and the activity of tyrosine aminotransferase (TAT) were examin ed in the liver of intact and adrenalectomized rats exposed to 41 degr ees C whole body hyperthermic stress. In glucocorticoid-deprived anima ls, stress-induced decrease in the cytoplasmic steroid binding was fol lowed by parallel increases in its nuclear binding and TAT activity, s uggesting a stimulation of TAT gene transcription by the GR in the abs ence of the ligand. In intact animals, however, a diminution of the st eroid binding in the cytosol, its unchanged nuclear binding and an imp airment of TAT activity were observed upon the stress. The results imp ly that stress could elicit different structural or functional alterat ions of unliganded vs liganded GR. (C) 1996 Academic Press Limited