Ligand‐gated ion channels (LGICs) for a variety of neurotransmitters play major roles in oligodendroglial‐lineage cell physiology and pathophysiology 31 and we therefore examined the functional expression of AMPARs, GABAARs, NMDARs, and strychnine‐sensitive glycine receptors (GlyRs) in our cultures. Application of AMPA (10 μM) elicited small inward currents in PDGFRα+‐OPCs which could be potentiated (1,320 ± 500%; n = 5) in the presence of the AMPAR selective potentiator, cyclothiazide (10 μM; Fig. 6A). The AMPAR antagonist 6‐cyano‐7‐nitroquinoxaline‐2,3‐dione (CNQX) (30 μM) blocked these agonist‐evoked currents. All cells examined responded to AMPA, although AMPAR current densities decreased as OPCs matured to oligodendrocytes (Fig. 6C). Responses to NMDA (100 μM, in the presence of glycine (50 μM)) were not observed in either PDGFRα+‐OPCs (n = 6) or week 3 O4+‐oligodendrocytes (n = 8; Fig. 6B, 6C). GABA (100 μM) evoked responses in 63% in PDGFRα+‐OPCs (n = 8) and 74% in O4+‐oligodendrocytes (n = 19) which were blocked by picrotoxin. GABAAR current densities decreased during OPC maturation (Fig. 6B, 6C). Applications of glycine (100 μM) did not elicit responses in PDGFRα+‐OPCs or week 3 O4+‐oligodendrocytes (data not shown).
