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. 2009 Jul 8;29(27):8764–8773. doi: 10.1523/JNEUROSCI.1014-09.2009

Figure 4.

Figure 4.

PS-induced changes in LTP/LTD induction are correlated with changes in the NR2A/NR2B ratio. A, Summary of data comparing the NR2A/NR2B ratio in cells primed with stimulations with that in interleaved control (con.) cells. The 1 and 5 Hz LPS led to a decreased NR2A/NR2B ratio. Conversely, 50 and 100 Hz HPS led to an increased NR2A/NR2B ratio. Stimulations at 10 and 20 Hz failed to induce marked alterations in the NR2A/NR2B ratio. *p < 0.05; ***p < 0.001; ANOVA and post hoc LSD test. Representative traces at the top show measurements of the NR2A/NR2B ratios using the NR2B-specific antagonist ifenprodil (ifen.; 3 μm). This measurement of the NR2A/NR2B ratio was conducted at the same time point that subsequent LTP/LTD was induced with pairing protocols. The NR2B-specific antagonist ifenprodil (3 μm) abolished the EPSC components mediated by the NR2B subunit, which was measured as the difference of area under the EPSC curves before and after ifenprodil application (left). The effect of ifenprodil on NR2B was confirmed by the shortened current decay time after ifenprodil treatment (right). B, The mean (±SEM) effects of PSs of 600 pulses at various frequencies delivered to the Schaffer fibers on the normalized (Norm.) NR2A/NR2B ratio measured in CA1 neurons at the same time point that subsequent LTP/LTD was induced with pairing protocols after PSs. C, Plot of averaged data showing LTP magnitude as a function of the NR2A/NR2B ratio. The potentiation magnitude after LTP production and the level of NR2A/NR2B ratios set by PSs were negatively correlated, which fit with the equation Y = −77.0X + 206.4 (r = −0.93; p < 0.01). D, Plot of averaged data showing the LTD magnitude as a function of the NR2A/NR2B ratio. LTD production and the level of the NR2A/NR2B ratio were positively correlated, which fit with the equation Y = 38.0X − 43.3 (r = 0.97; p < 0.001).