Glutamate metabolism, release, and quantal transmission at central excitatory synapses: implications for neural plasticity.

Glutamate is thought to act as a neurotransmitter at several excitatory synapses in the brain. Available knowledge reveals complex intercompartmental dynamics of glutamate, which is synthesized, accumulated and released by presynaptic elements, activates postsynaptic receptors, and is eventually re-uptaken and interconverted to glutamine by the participation of surrounding glial cells. The postsynaptic reactions to physiological release of glutamate during neurotransmission are considered in relation to the quantal approach, which is revealing unsuspected complexity in central synaptic mechanisms. This issue is particularly important in view of its implications in the study of long-term synaptic modifications.