(A) Representative agonist induced (EC20–30) currents from oocytes expressing GLIC, GABAρ, and GLIC–ρII in the absence and presence of neurosteroid isomers 5α-THDOC (upper panel) and 5β-THDOC (lower panel). Black bars represent agonist application (pH 5 for GLIC, 1µM GABA for GABAρ and pH 6 for GLIC–ρII). Open bars represent neurosteroid application, 30µM for GLIC and GLIC–ρII and 10µM for GABAρ. (B) Summary of neurosteroid modulation of EC20–30 currents from GLIC, GABAρ, GLIC–ρII and GLIC–ρIII, [(I+DRUG/I)−1]×100 (%). 5α-THDOC potentiated EC20–30 agonist mediated GABAρ currents but inhibited GLIC, GLIC–ρII and GLIC–ρIII currents. 5β-THDOC inhibited EC20–30 agonist mediated GABAρ and GLIC currents but potentiated GLIC–ρII and GLIC–ρIII currents. Data are mean±SEM from ≥ 3 oocytes.