Stress-induced increase of extracellular levels of cyclic AMP in rat cortex.

Previous studies have suggested that stress may increase levels of cyclic AMP (cAMP) in the brain but these findings have been controversial due to the use of stressful procedures to inactivate brain enzymes. The present experiment therefore used a non-stressful technique, microdialysis, to assay extracellular levels of cAMP in the rat cortex after stress. Experiments were conducted 2 days after implantation of probes in the frontal cortex. Significant increases were found after the mild stressors of restraint or intraperitoneal injection of saline suggesting that increased tissue levels of cAMP had occurred. These responses were potentiated by local infusion of the phosphodiesterase (PDE) inhibitor, rolipram. It is concluded that one or more adenylate cyclase-coupled receptors in the cortex is activated by mild stress and that this activation can be detected in vivo by microdialysis.