STUDIES ON THE FUNCTIONAL ROLE OF ADENOSINE 3', 5'-MONOPHOSPHATE, HISTAMINE AND PROSTAGLANDIN E1 IN THE CENTRAL NERVOUS SYSTEM

Abstract

A wide variety of hormones, such as epinephrine, glucagon and ACTH, increase the intracellular concentration of cyclic AMP in several tissues and cyclic AMP induces similar effects to those of many hormones (1, 2). Thus it has been proposed that cyclic AMP mediates the responses of these hormones. Increased concentrations of cyclic AMP in tissues are caused by enhanced adenyl cyclase activity or suppressed phosphodiesterase activity. The activities of these enzymes are known to be higher in the brain than in other tissues (3, 4). Cyclic AMP was previously reported by Siggins, Hoffer and Bloom (5) to interfere with neuronal activity in the cerebellum of rats. It is conceivable that cyclic AMP may play a role in regulating the activities of the cells of central nervous system as an intracellular mediator of responses to transmitters and hormone-like compounds. In support of this Kakiuchi and Rall (6) reported that on incubation of slices of rabbit cerebral cortex with histamine a large amount of cyclic AMP accumulated in the slices. Recently similar results were reported by other investigators (7–9).