EXTRACELLULAR ATP AS A NEUROTRANSMITTER - ITS ROLE IN SYNAPTIC PLASTICITY IN THE HIPPOCAMPUS

Growing evidence indicates that ATP may play a very important role in Long-Term Potentiation (LTP), a neurophysiological process that has be en implicated in memory formation. LTP is an enhancement of synaptic s trength induced by a specific pattern of high frequency stimulation, o r by application of exogenous ATP. In the hippocampus LTP-inducing sti mulation is accompanied by a massive, Ca2+-dependent release of ATP fr om presynaptic terminals. Released extracellular ATP may either intera ct with numerous types of ATP receptors present on the neuronal surfac e, or serve as a substrate for ecto-protein phosphorylation. The resul ts of combined electrophysiological and biochemical experiments indica te that participation of extracellular ATP in the ecto-protein phospho rylation process is most likely involved in the permanent amplificatio n of the synaptic response in the hippocampus.