Figure 7.

Distribution histograms of synapses containing different numbers of GluR1 or GluR2 immunogold particles. (A) Histogram bars represent average relative frequencies of synapses without GluR1 gold particles (0 particles) or containing from 1 to 9 gold particles in control and FZP-withdrawn animals. The distributions of GluR1 particles in synapses from control (black bars) and FZP-withdrawn rats (open bars) were compared by χ² analysis and a significant overall increase in the number of synapses with a higher content of gold particles was detected in FZP-withdrawn rats compared to controls (χ²=59.4, df=9, p=0.000). The fraction of synapses lacking GluR1 immunogold labeling was significantly lower in asymmetric synapses from FZP-withdrawn rats compared to control rats (**p<0.01, Mann-Whitney U test). A significant increase in the fraction of synapses expressing 7 and 8 gold particles was also observed after FZP withdrawal (**p<0.01, Mann-Whitney U test). (B) The distributions of GluR2 immunogold particle content also significantly different in CA1 synapses from between control and FZP-withdrawn animals (χ²=77.8, df=9, ***p=0.000). However, the observed fraction of synapses lacking GluR2 particles (0 particles) was not significantly different between groups (p=0.86, Mann-Whitney U test), nor were there differences in any fraction of labeled synapses with a given number of gold particles (1 to ≥9; p>0.05, Mann-Whitney U test).