Figure 5.

Tonic GABA currents of adult NG2 glia show higher sensitivity to α5 subunit blockage. (A) Original recordings of tonic currents in NG2 glis at p10 (upper trace) and p60 (bottom). The trace was smoothened by a boxcar averaging algorithm. Nipecotic acid (1 mM) was added to the bath solution for at least 3 min to increase extracellular GABA levels. Subsequent addition of bicuculline (20 µM) induced a positive shift of holding current. The dashed line indicates the average of the labeled range in the presence of nipocotid acid (light gray) and nipecotic acid/bicuculline (dark gray), respectively. Scale bar: 10 pA, 50 s. (B) Bar graph showing the mean shift of holding current (p10: 13.72 ± 17.61 pA, n = 17, N = 5; p60: 14.15 ± 11.14 pA, n = 14, N = 4). There was no difference between ages (t-test; p = 0.09). (C) Original recording demonstrating the effect of the α5 subunit specific blocker, α5IA, in NG2 glia of juvenile (upper trace) and adult mice (bottom). Nipecotic acid was applied as described in (A). Traces were smoothened as mentioned in (A). Subsequent application of α5IA (500 nM) partially blocking tonic currents. After another 2 min, bicuculline (20 µM) was added to the bath solution to block the remaining tonic current. Dashed line indicates the average of the labeled range in the presence of nipocotid acid (light gray), after addition of α5IA (orange) and bicuculline (dark gray), respectively. Scale bar: 10 pA, 50 s. (D) Bar graph showing the relative effect of α5IA on GABAergic tonic current. The shift in holding current induced by α5IA was normalized to that induced by bicuculline. The relative effect of α5IA was higher in p60 mice (p10: 0.18 ± 0.2; n = 9, N = 5; p60: 0.4 ± 0.18, n = 9, N = 4). Two-sample t-test, * p < 0.05.