Cyclic AMP and cyclic GMP response to stress in brain and pituitary: stress elevates pituitary cyclic AMP.

Male rats were exposed to six stressors (saline injection, cold, forced running, Formalin injection, immobilization, electric footshock) for 15, 30, or 60 min. Following sacrifice by microwave irradiation, cyclic AMP and cyclic GMP levels were measured in pituitary, pineal and 8 regions of rat brain. All stressors except saline increased plasma corticosterone, plasma prolactin and pituitary cyclic AMP levels compared to control animals. The magnitude of the pituitary cyclic AMP response was highly correlated with the intensity of the stress as determined by the levels of plasma prolactin. Electric footshock increased pituitary cyclic AMP levels over 10 fold and plasma prolactin over 60 fold. Cyclic AMP levels in other brain regions were not altered. Cerebellar cyclic GMP was increased only by stressors that involved increased motor activity.