EFFECTS OF ADENOSINE ON DEPOLARIZATION-INDUCED RELEASE OF VARIOUS RADIOLABELED NEUROTRANSMITTERS FROM SLICES OF RAT CORPUS STRIATUM

The effects of adenosine on the K+ -induced release of radiolabelled dopamine (DA), acetylcholine (ACh), serotonin (5-HT) and GABA from rat striatal slices were examined. Adenosine dose-dependently (10-6-10-4M) inhibited the release of 3H-DA, 14C-ACh and 3H-5-HT. However, the effects were small e.g. at 10-5 M adenosine caused reductions of about 15%. The release of 14C-GABA was not affected by adenosine at concentrations up to 10-5M. Theophylline (10-4 M) antagonized the inhibiting effect of adenosine on 14C-ACh release. Antagonism by theophylline of the inhibitory effects of adenosine on 3H-DA and 3H-5-HT release could not be demonstrated, possibly because theophylline by itself caused some inhibition of release in these cases. The data are discussed in relation to a postulated role of adenosine in central neurotransmission. The possibility is suggested that in the CNS purinergic receptors may be involved in the regulation of synaptic transmission in a proportion of noradrenergic and cholinergic neurones and that the central effects of theophylline may in part be related to an interaction with such receptors. © 1979.