PURINOCEPTORS IN THE NERVOUS-SYSTEM

The purine nucleoside adenosine and the purine nucleotide ATP play different roles in the nervous system. Adenosine acts on a family of G protein coupled receptors, collectively called adenosine receptors or P-1 purinoceptors. Four members of this family have been cloned and pharmacologically characterized: A(1), A(2A), A(2B) acid A(3) Their distribution, pharmacology and biological roles are briefly discussed. In particular, the evidence that adenosine acting at A(2A) receptors regulates the release of several neurotransmitters and that adenosine acting at AZA receptors modulates dopaminergic transmission is summarized. ATP acts on receptors called P-2 purinoceptors, which appear to fall into at least two main families - G protein coupled receptors and intrinsic ion channels. Their subclassification is becoming clearer as receptors are cloned and new selective agonists and/or antagonists are becoming available. There is an interesting potential for development of drugs targeted at purines or their receptors.