GLIAL CONTRIBUTIONS TO EXCITATORY NEUROTRANSMISSION IN CULTURED HIPPOCAMPAL CELLS

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.