Figure 6.
Effects of DA on outward currents elicited by exogenous GABA in D2KO mice. A, Effects of DA (10 μm; filled bar) and bicuculline (20 μm; open bar) on outward currents induced by iontophoretic application of GABA (1 mm) on GP neurons in the presence of TTX (1 μm) and 2-OH-saclofen (100 μm), a selective GABAB receptor antagonist. Evoked outward currents considerably fluctuated, but DA effectively and reversibly suppressed the currents. Each trace, taken at the indicated time point (1-5), represents outward current before, during, and after the application of DA or bicuculline. Calibration: 0.4 nA, 400 msec. B, Normalized outward currents were plotted with the application of DA for the period indicated by the bar (filled circles; n = 5) or with control vehicle (open circles; n = 5). C, Summarized histograms show the inhibitory effect of DA on the amplitude of outward currents. *p < 0.05; unpaired Student's t test.