Abstract
A simple, sensitive, radioisotopic method to measure the formation of adenosine 3’,5’-cyclic monophosphate (cyclic AMP) by brain slices is described and evidence for its specificity is given. The method was used to study the effect of several drugs and hormones on the accumulation of cyclic AMP in slices from several regions of the brain of different animal species. The marked T stimulatory effect of histamine on the formation of cyclic AMP in rabbit and guinea pig brain cortex is peculiar to these species and does not occur in the brain cortex of rat, mouse, cat and monkey. In the cortex of these last species, norepinephrine (NE) has been found to be the most active agent in increasing cyclic AMP formation. Marked differences between brain regions of different animal species were also found. Although theophylline increases cyclic AMP in various other tissue preparations, it does not enhance the histamine or NE induced formation of cyclic AMP in incubated brain slices.