Effect of hyperthermia on epididymal cyclic AMP levels in diabetic non-diabetic and hypophysectomized rats

The effect of elevated body temperatures on the concentrations of epididymal cyclic AMP levels in non-diabetic, diabetic and hypophysectomized rats was studied. Cyclic AMP levels were increased during hyperthermia in all animals examined. This increase in epididymal cyclic AMP concentration was not seen in animals that had been supplemented with exogenous insulin prior to the experiment. The effect of pituitary lipolytic hormones on epididymal cyclic AMP levels was also investigated. Significant elevations of epididymal cyclic AMP levels were observed in hypophysectomized rats during hyperthermia indicating that pituitary hormones are not essential in causing these increases. Extrapituitary hormones, such as glucagon, might be responsible for epididymal cyclic AMP increases. Increases in epididymal cyclic AMP levels may therefore be the result of the reduction of blood insulin and concomitant increases of lipolytic hormones of both pituitary and extrapituitary origins.