Glutamate as a neuron-to-glial signal for mitogenesis: role of glial N-methyl-D-aspartate receptors.

The presence on glial cells of receptors for neurotransmitters suggests the capability of neuron-to-glial signalling. Here, we asked whether the retinal transmitter, glutamate, may serve as a mitogenic signal for human retinal glial cells. Using cultured glial from the adult postmortem retina, we found that glutamate stimulated the proliferation of these glial cells. Pharmacological experiments indicated that this proliferative effect involved activation of N-methyl-D-aspartate (NMDA) receptor channels. Activation of NMDA receptors on retinal glial cells may mediate a proliferative response of these cells to pathophysiologic conditions causing a sustained elevation of glutamate.