Adenosine receptor and beta-adrenoceptor stimulation increases noradrenaline synthesis in hippocampal synaptosomes

The synthesis of noradrenaline was measured, using high-performance liquid chromatography with electrochemical detection, in synaptosomal fractions prepared from rat hippocampus. Noradrenaline synthesis is depressed by adenosine deaminase and the adenosine antagonist, 8-phenyltheophylline and stimulated by the adenosine agonist, 2-chloroadenosine. β-Adrenoceptor stimulation also increases synthesis. The adenosine receptors and β-adrenoceptors do not interact. Both receptor-mediated effects are distinct from, and additive with, the acceleration of synthesis by potassium-depolarisation.The results are compatible with an adenosine-receptor and β-adrenoceptor stimulation of adenylate cyclase, leading to a cyclic AMP-mediated activation of tyrosine hydroxylase.