Psychotropic Drugs and Cyclic AMP in the Brain

Abstract

Brain tissue has rather high activities of adenylate cyclase and phosphodiesterase and possesses relatively high concentrations of cyclic[c]AMP. Numerous studies dealing with the regulation of synthesis and degradation of cAMP in the brain have been conducted. The implication that cAMP plays a major functional role in the CNS has made the cAMP-generating system a favorite object for studies on the mechanism of action of psychotropic drugs. There are mainly 4 possibilities of how drugs can directly affect levels of cAMP in tissue: by modification of the enzymic properties of the adenylate cyclase; by alteration of phosphodiesterase activity; by interacting with receptors for neurotransmitters which are coupled to the adenylate cyclase; and by unspecific membrane effects. Drugs may change the metabolism and content of neurotransmitters to such an extent that in response to it, adaptive changes occur in the cAMP-generating system.