Glycine triggers an intracellular calcium influx in oligodendrocyte progenitor cells which is mediated by the activation of both the ionotropic glycine receptor and Na+ -: dependent transporters

Using fluo-3 calcium imaging, we demonstrate that glycine induces an increase in intracellular calcium concentration ([Ca2+](i)) in cortical oligodendrocyte progenitor (OP) cells. This effect results from a calcium entry through voltage-gated calcium channels (VGCC), as it is observed only in OP cells expressing such channels, and it is abolished either by removal of calcium from the extracellular medium or by application of an L-type VGCC blocker. Glycine-triggered Ca2+ influx in OP cells actually results from an initial depolarization that is the consequence of the activation of both the ionotropic glycine receptor (GlyR) and Na+-dependent transporters, most probably the glycine transporters 1 (GLYT1) and/or 2 (GLYT2) which are colocalized in these cells. Through this GlyR- and transporter-mediated effect on OP intrcellular calcium concentration [Ca2+](i), glycine released by neurons may, as well as other neurotransmitters, serve as a signal between neurons and OP during development.