ALTHOUGH many glial cells possess neurotransmitter receptors and trans
porters(1-5), little is known about glial participation in neurotransm
ission. To explore this issue, we recorded neuronal autaptic(6,7) and
glial responses from cultured hippocampal single-neuron micro-islands(
6,7). Excitatory synaptic events activate rapid electrogenic glial glu
tamate transporter currents similar to those elicited by exogenous glu
tamate in other preparations. We show here that glial transporter resp
onses may be used to sense changes in presynaptic efficacy and that gl
ial uptake helps to remove synaptically released glutamate, thereby co
ntributing to the termination of excitatory synaptic currents under ce
rtain conditions. These observations provide a framework for understan
ding the role of glia in both normal and pathological processes.