Effects of changing levels of glucocorticosteroids on heat exposure in rabbit

Rabbits exposed for one hour to a temperature of 40degrees Cand 35-37% humidity showed elevated plasma osmolality and pH. Most of the animals were not able to withstand the heat. Dexamethasone-treated rabbits under the same conditions withstood the heat better and their plasma pH and osmolality remained constant. Metopirone-treated rabbits withstood the heat and showed a rise in plasma osmolality and a slight change in plasma pH. The highest rise in rectal temperature was observed in the metopirone-treated rabbits. Only the untreated animals were unable to regain pre-exposure rectal temperature. The results suggest that high levels of glucocorticosteroids enhance neurogenic and metabolic mechanisms which have protective functions during acute exposure to heat.