Cyclic nucleotides in the rat neostriatum: Push-pull perfusion studies

A push-pull perfusion technique was employed for in vivo study of adenosine 3′,5′-monophosphate (cAMP) and guanosine 3′,5′-monophosphate (cGMP) in the rat caudate nucleus. Addition of dopamine to the perfusion fluid elicited dose-dependent increases of both cAMP and cGMP perfusate concentrations. In separate experiments, it was found that pretreatment of animals with the dopamine antagonist, pimozide, significantly depressed both nucleotide responses to dopamine perfusion over the dose range studied. Mechanistic interpretations of the observations are considered. The push-pull perfusion technique appears to provide an extremely useful means of examining extracellular cyclic nucleotide levels in a discrete brain region, in vivo, under dynamic conditions.