Corticosterone tissue-specific response in Sprague Dawley rats under acute heat stress.

Our study evaluated the physiological responses to acute heat stress in rats via body temperature and tissue corticosterone levels, and investigated the relative tissue response to heat stress based on corticosterone. Body temperature of rats under 22 °C (control) and 42 °C for 30 (H30), 60 (H60) and 120 min (H120) was measured. Correspondingly, corticosterone was analyzed in 11 tissues (adrenal, brain, heart, kidney, liver, lung, leg muscle, blood, stomach, spleen and small intestine). Analysis of variance and correlations were conducted on body temperature and corticosterone levels. The receiver operating characteristic (ROC) analyzed the thermo-sensitivity via corticosterone. Body temperature of rats in H30, H60 and H120 groups were higher (P < 0.05) than the control. Compared to the control, corticosterone levels of heart, stomach and small intestine at H30, corticosterone levels in adrenal, leg muscle and stomach at H60, and corticosterone levels in adrenal, heart, lung, stomach and small intestine at H120 differed (P < 0.05). The corticosterone in lung tissue was an excellent indicator of acute heat stress, with an area under the curve (AUC) of 1.00 at H60 and H120. In order to improve the prediction of acute heat stress, models combining corticosterone levels of multiple tissues reached an AUC of 1.00 for H30, and the sensitivity increased to 100% for H60 and H120. In conclusion, changes in the patterns and thermosensitivity of corticosterone levels associated with the duration of heat stress across body tissues were evidenced. The single and multi-organizational corticosterone models serve as indicators for evaluating heat stress across different time periods.