Hyperthermic stress affects the thermal modulation of glucocorticoid-receptor affinity

In vitro binding of a steroid hormone (triamcinolone acetonide) to hepatic glucocorticoid receptors was studied in liver cytosols prepared from untrea ted control rats and rats sacrificed after being exposed in vivo to whole b ody hyperthermia (41 or 42 degreesC). Positive temperature modulation of gl ucocorticoid-receptor affinity (decrease of affinity with increasing temper ature) was well expressed in all preparations. In preparations from hyperth ermic rats, alterations of a possible functional (adaptive) significance ha ve been recorded: the amplitude of positive thermal modulation was reduced, and its lower-temperature limit shifted towards higher temperatures. (C) 2 001 Elsevier Science Ltd. All rights reserved.