Figure 10.
Requirement of NMDAR activation for the increase in neuron-neuron connectivity but not for the increase in surface NR2B-NMDARs. A, Neuron-neuron connectivity was measured as described in Figure 2. Neurons were untreated (Ctrl) or treated with TTX (TTX) or TTX plus 200 μm ketamine (TTX + ketamine) for the last 2 d of a 20 d culture (mean of 3 series of experiments; 20.0 ± 5.9, 76.7 ± 4.4, and 33.4 ± 2.9% for control, TTX, and TTX + ketamine, respectively; n = 4 series; *p < 0.05). B, Ifenprodil-sensitive currents were measured as described in Figure 5. Averaged currents of control (Ctrl), TTX-treated (TTX), and TTX plus ketamine-treated (TTX + ketamine) neurons (n = 8-12; *p < 0.05) are indicated. C, Averaged ifenprodil sensitivity of NMDA currents in control, TTX-treated, and CNQX-treated neurons (mean of 3 series of experiments; Ctrl, 28.9 ± 3.6%; TTX, 49.5 ± 1.8%; CNQX, 49.3 ± 1.6%; *p < 0.05). D, Averaged ifenprodil sensitivity of NMDA currents in control, TTX-treated, and both TTX- and AMPA-treated neurons (mean of 3 series of recordings; Ctrl, 21.4 ± 1.7%; TTX, 41.3 ± 4.5%; TTX plus AMPA, 17.9 ± 3.6%; *p < 0.05).