Psychological stress increases pituitary cyclic AMP.

Exposure to physical stressors has been shown to produce increases in pituitary cyclic AMP in laboratory rats. In this experiment, the generality of these findings has been extended to include a psychological stressor, defined as returning the animals to a situation in which they had been exposed to footshock for four days. Rats in the psychological stress group exhibited increases in pituitary cyclic AMP and in plasma corticosterone and prolactin which were similar to those seen in animals that received the physical stressor on the test day. At present it is not known whether the effects are due to associative conditioning or to sensitization of the neuroendocrine system following repeated presentations of the physical stressor.