Location of adenosine release and adenosine A2 receptors to rat striatal neurons.

Three types of striatal lesions were performed to determine the site of adenosine synthesis and release and the location of adenosine A2 receptors: decortication; injection of 6-hydroxydopamine (6-OHDA) into the median forebrain bundle; and injection of kainic acid into the striatum. The parameters measured in the striatum were content of adenosine, activation of adenylate cyclase by N6-(L-phenylisopropyl) adenosine (PIA) and release of endogenous adenosine from a perfused slice. Decortication and 6-OHDA had only minimal affects on the parameters measured. In contrast, kainic acid injection into the striatum decreased the content of adenosine, the release of adenosine from a slice preparation and diminished the ability of PIA to activate adenylate cyclase. We postulate that neurons which synthesize and release adenosine, originate in the striatum. The adenosine receptors appear to be of the adenosine A2 type and they may be located on adjacent neurons or on the adenosine releasing neurons themselves.