Given the importance of AMPARs to oligodendrocyte‐lineage cell physiology and disease 32, 33, 34, we characterized the AMPAR composition. We initially determined that the expression of GluA2, 3 and 4 subunit mRNA was increased relative to GluA1 in oligodendrocytes compared with OPCs. The GluA2 subunit mRNA was the most prominently expressed subunit in the oligodendrocyte. In agreement with an increase in GluA2(R) expression from previous studies 55 (although see ref. 31), maturation of human oligodendrocytes is associated with a decrease in the unitary conductances of AMPARs. The most parsimonious explanation for this change in conductance is the increase in expression of edited GluA2(R) subunits expressed in AMPAR complexes as the conductance values for week 3 oligodendrocytes correspond well to those of recombinantly expressed heteromeric GluA2(R)‐containing AMPARs 56. In agreement with changes in unitary AMPAR conductance estimates, we observed a reduction in inhibition of AMPAR‐mediated currents by NASPM, an antagonist which blocks AMPARs that do not contain GluA2(R) subunits. While these data indicate AMPARs predominantly expressed in OPCs are GluA2(R)‐lacking and oligodendrocytes are GluA2(R)‐containing, our data suggest that small populations of
