Presynaptic P2 receptors?

Although the emphasis in ATP research has been on postjunctional receptors, there is also evidence for presynaptic receptors regulating transmitter re lease in the autonomic nervous system. Recent work has attempted to identif y similar mechanisms in the central nervous system. Some of the existing re sults can be explained by the metabolism of nucleotides to adenosine or ade nosine 5'-monophosphate (AMP). However, studies of presynaptic effects usin g sensitive electrophysiological tests such as paired-pulse interactions in dicate that nucleotides can act at presynaptic sites, but that their effect s may be mediated by a release of adenosine. Results are also described whi ch indicate that, under some conditions, nucleotides can mediate phenomena such as long-term potentiation, which probably involves a significant presy naptic element. In part these effects may involve a nucleotide-induced rele ase of adenosine and the simultaneous activation of P1 and P2 receptors. (C ) 2000 Elsevier Science B.V. All rights reserved.