ATP as a presynaptic modulator

There is considerable evidence that ATP acts as a fast transmitter or co-tr ansmitter in autonomic and sensory nerves mostly through activation of iono tropic P2X receptors but also through metabotropic P2Y receptors. By analog y, the observations that ATP is released from stimulated central nervous sy stem (CNS) nerve terminals and that responses to exogenously added ATP can be recorded in central neurons, lead to the proposal that ATP might also be a fast transmitter in the CNS. However, in spite of the robust expression of P2 receptor mRNA and binding to P2 receptors in the CNS, the demonstrati on of central purinergic transmission has mostly remained elusive. We now r eview evidence to suggest that ATP may also act presynaptically rather than solely postsynaptically in the nervous system. (C) 2000 Elsevier Science I nc. All rights reserved.