Catecholamine Induced Increase of Cyclic Adenosine 3′,5′‐monophosphate in Rat Brain in Vivo

Four catecholamines injected into the cerebral ventricles increased the content of cyclic adenosine 3′,5′‐monophosphate (cAMP) in vivo in the whole brain of rats. The highest rise (2.6‐fold) was measured 2 min after an injection of 100 μg epinephrine. Isoproterenol and norepinephrine were less active and dopamine hardly increased the cAMP level. These results are compatible with the view that physiological actions of catecholamines in the nervous system may be mediated by an increase of CAMP.