Fig. 6: The NT-induced increase in neuronal excitability is mediated by inhibiting TWIK-1/TASK-3 heterodimeric channels.

a Bath application of NT-mediated membrane depolarization of granule cells. A representative response of the membrane potential to stepwise current injections was recorded from naive DGGCs (n = 15, N = 3) or DGGCs infected with Ad-Sc shRNA (n = 16, N = 3), Ad-TWIK-1 shRNA (n = 17, N = 3), Ad-TASK-3 shRNA (n = 15, N = 3), or both Ad-TWIK-shRNA and Ad-TASK-3 shRNA (n = 14, N = 3). The resting membrane potential of these cells was maintained at −70 mV by constant current injections, and depolarizing currents were then injected stepwise at 5-pA increments until the membrane potential reached the firing threshold. b, c Analyzed bar charts of spike numbers at 105 pA for a. b Resting membrane potential values of the whole-cell currents in naive dentate gyrus granule cells (n = 15 cells, N = 3 mice) and cells expressing Sc shRNA (n = 16 cells, N = 3 mice), TWIK-1 shRNA (n = 17 cells, N = 3 mice), TASK-3 shRNA (n = 15 cells, N = 3 mice), or TWIK-1/TASK-3 shRNAs (n = 14 cells, N = 3 mice). c The extent of changes in the number of spikes following NT application in naive and Ad-Sc shRNA-infected DGGCs was larger than those in DGGCs transfected with Ad-TASK-1 shRNA alone, Ad-TWIK-1 shRNA alone, or both Ad-TWIK-1 shRNA and Ad-TASK-3 shRNAs. The data for Ad-TASK-3 shRNA alone, Ad-TWIK-1 shRNA alone, and both Ad-TWIK-1 shRNA and Ad-TASK-3 shRNAs showed no change in the numbers of spikes. The recordings were obtained in artificial cerebrospinal fluid containing 50 µM D-AP5, 10 µM CNQX, 10 µM bicuculline, 10 µM CGP55845, 2 mM TEA, and 0.5 mM NiCl₂, with a pipette solution containing 5 mM QX314. All the data are presented as the means ± SEM. ***P < 0.001 was considered statistically significant