The functions of ATP receptors in the hippocampus

The possible involvement of adenosine 5'-triphosphate (ATP) receptors in the function of the hippocampus is reviewed. The involvement of these receptors in the hippocampus is suggested by data that ATP is released from hippocampal slices, and that it also induces fast synaptic currents in cultured hippocampal neurons and long-lasting enhancement of the population spikes. In addition, ATP is released by glutamate-stimulation which leads to an increase in intracellular Ca²⁺ in hippocampal cells, ATP also inhibits the glutamate release in cultured hippocampal neurons, and it has been shown that several mRNAs for certain types of P(2X)-purinoceptors are present in this area. It is therefore likely that ATP may play a role in the modulation of synaptic efficiency in the hippocampus. Microglia cells are activated by the stimulation of ATP and releases plasminogen but not nitric oxide (NO). It has been reported that plasminogen promotes the development of mesencephalic dopaminergic neurons and enhances neurite outgrowth from explants of neocortical tissue. The possibility that ATP protects brain function from over stimulation is discussed.